When you say the class system is not sustainable - do you mean morally, politically, economically? — Judaka
In this context I mean ecological sustainability.
When we look at Amazon, we see a company utterly destroying local businesses that cannot compete and this has been happening since the industrial revolution. If mass production could be competed with by "local living" then why has this happened and what's going to happen differently? — Judaka
The usual answer is that the industrial revolution depended on the enclosure movement of kicking peasants off the land. Bourgeois economic theory both condemns Feudal definitions of ownership (serfs and estates etc.) but takes for granted the good Lords had a right to kick everyone off the land.
Likewise, bourgeois economic theory takes for granted that "urban culture" is superior to "rural culture" and the movement to the cities is just a natural cultural evolution to a better place. However, if we look closely, most people that have emigrated to cities over in the industrial revolution went to slums and horrifying working conditions and were clearly better off as peasants.
A peasant is not compatible with the capitalist mode of production, as peasants can produce food for themselves by gardening, build their own houses, make their own chairs and baskets etc. (of course, by "rural living" here I do not mean agribusiness that turns the land into a substrate for maximum commodity production, such "farms" and the illegal immigrants that work on them is not an example of peasant life and organization, of course with many terms and conditions on the "Lords" land, that existed in feudal times).
Therefore, we come to the question of efficiency for what? Efficient at living? or efficient at producing as many commodities as possible? Way more commodities than anyone needs.
In other words, in a narrow perspective, large industrial production seems efficient as it has massive throughput, but in a wider perspective it is inefficient in terms sustainable use of raw materials as well as inefficient in terms of producing "what people need" (rather than simply "producing as much as possible"; the dreaded overproduction).
We have seen since the industrial revolution how overproduction is absorbed: war, planned obsolescence, growing the population (at first a happy side-affect of medicine, and later by a policy of immigration), manipulative marketing and debt.
Bourgeois economics assumes people need to consume commodities all the time, that this is a natural thing to happen, but if we look closely at peasants of the past (as well as people who happen or choose to be in similar circumstances today - of course they don't call themselves peasants, but "homesteaders") such peasant economics naturally invites capital investment. Rural dwellers buy tools to do things for themselves; it's simply cheaper and quicker to learn basic maintenance and fabrication skills than hire someone for every task. Any food grown locally is far cheaper than food that needs to be picked, stored, transported (to multiple locations); any food waste is composted (without the re-centralization transport problem) simply because that's the easiest thing to do and the benefits are obvious. The idea of regular consumption has obvious immediate negatives since shops are not just down the road, and if one needs to (pay) to go someone regularly to get stuff, the question naturally arises whether there's some investment that can replace this commodity (i.e. planting some apple trees and making one's own apple juice).
Why this doesn't happen (in the West) is not an economic question, but the "who owns the land" question. In the West today if we talk about "gardening" and "fishing" the assumption is that we're talking about wealthy people that garden and fish for fun, not to save money; likewise, if we talk about "skiing" we assume we're talking about wealthy people skiing for fun, not a convenient rural transport winter technology. So, the question arises that if the wealthy are constantly playing at being peasants for fun, shouldn't we just organize society so that everyone can do these things both to have fun and save money: that we make our rural landscapes like the idyllic beautiful places where the rich go for vacation, just that people happen to also live there?
So, much more can be said why such a "return to the land" is more efficient in terms of resource allocation: that it's easy to garden in bio-diversity based way that's good for nature whereas it's hard to produce commodities with the same methods ("things" aren't produced in sufficient quantities at the same place to warrant the capital investments in sorting, packaging, storing and transport technology; such food is only fit to be picked and eaten, or stored in jars; totally useless to the capitalist system), that with more people living in such a way a network effect of trade occurs making it even more efficient (local artisan production displaces imported commodities), that lowering transport of commodities and commuting means both lowering the cost of living but also lowering the cost of transport infrastructure (which can still there, but with radically less throughput, it is much less costly and less environmentally damaging), and new means of production (3D printing, CNC machining etc.) constantly reduce the scale in which precision manufacturing is economically possible (further reducing the need of importing commodities), and also that communication technology would still allow lot's of existing jobs today to be done at-distance and further increase foreign exchange of the community.
The problem is of course land ownership. Since the industrial revolution to now, land consolidation to remove communities living on the land to turn land from living spaces to substrate for commodity production, has been a violent affair (first through enclosures, second through arranging to financially ruin small farm and other peasant-like people, and third through letting natural disasters, like drought, and economic disasters do the dirty business without anyone needing to pay attention, as well as constantly flooding rural places with subsidized commodities, whether as the go-to market entry tactic or as well as state subsidy of capitalism in general, to ruin the local economies and increase commodity reliance), we don't see this much in the West anymore, as the process is largely complete.
Technologically speaking, it's easy to go out into the country-side, look at agribusiness desserts and draw up a technical plan to make small houses, forest gardens and permaculture, water management systems or rain capture and contouring, renewable energy systems, etc. Worse, it's easy to go to the suburbs and conclude that the same resources could support much more people and vibrant communities.
Why this doesn't happen is buying this land is expensive and the people who's life would improve don't have that kind of money. Indeed, not only do they not have that kind of money, but they are in debt and the kind of idyllic living described above assumes one does not need to maximize commodity production to keep up with debt repayments (that everyone one does in this sort of decentralized community living arrangements is not just to save money, but for fun, for community team building, as exercise of the body and mind; it saves money too, but does not maximize the kind of commodity production that is needed to payoff debts; only wage labour provides those circumstances for most people, and barely so as it may still take decades of full tilt, at the the psychological limits of commodity production to maybe payoff a few debts for most people).
Of course, society could simply cancel all debts, take the land from agribusiness and setup homesteaders with the tools and materials to live in an obviously ecologically superior way that is good for everyone, and can still produce more food for the whole of society (forest gardens and other forms of permacutlure are more productive than mono-culture fields, even on agribusiness own terms of pound per acre, but the comparison almost can't even be made if water and fossil inputs and nutrients per acre as output is used, not to mention biodiversity and regional ecological resilience tree transpiration and roots provides is included in the analysis).
Society does not even need an excuse to take agribusiness land (could just say "we don't give a shit about investor complaints; other people can win the "battle of ideas" if they put in the effort, there's no metaphysical basis to put some ideas of limits for the winning") but if it wanted and excuse it could say "the promise that privately owned land by profit maximizing capital would preserve the land for everyone must now be a promise kept; we will analyse everyone's land, and anyone that did not accomplish this preservation of the value on the land of biodiversity and soil nutrients forfeits their land as part of a retroactive social contract based on the same precedence that our precious bankers retroactively pardon themselves for financial crimes now and again" or then just use imminent domain and pay the land-owners in a currency in the process of collapse (imminent domain laws do not preclude ecological necessity as a basis for land appropriation; maybe they will in the near future, but society could simply choose to not give a shit about that anyways).
This isn't happening anytime soon, in the West, but there are places in the world where people aren't currently trapped in commodity production maximizing infrastructure, often still own their land as a community, and so everything I describe above is simply an immediate improvement of their tool-set, quality of life, foreign exchange, and local environment that they still feel intuitively and obviously dependent on, and improving the means of this kind of peasant production is relatively easily advanced through cooperation between those communities and western hippies who have a bit of capital, a "proper" education required for systems analysis to be sure things are actually better and not worse, and a fevered dream (that's from the malaria though, also a solvable problem).
As climate change, resource depletion, moves in the "great game", disrupt our global industrial commodity throughput device, more and more places will essentially drop out of capitalism regardless of whether the propaganda people jealously guard tells them it's a good thing or not, and what I describe above will become the only game in town. Of course, people may choose to play the game of raiding other towns down the dusty road of entitlement instead; time will tell us who wins.