I think it's important to note that there isn't an observably, historically satisfying definition of art. In something like Greek Mythology, the lines between art, religion, philosophy, and some kind of legendary, mystical expression of ancient history are blurred. Art served a religious function in the west dating back into the middle ages (earlier??), but it began to take on what we now categorize as a "high" form of art around the enlightenment, while still existing to serve the church and express religious concepts. "Secular" art did exist (love ballads whose melodies were later borrowed and made into sacred hymns, i.e. Be Thou My Vision), but the evolution of modern art in the west is descended, I think to a large degree, from the church: If you follow the historical thread of an art form, classical ("art") music, for instance, it moves from someone like Handel writing sacred music for the church (as well as secular operas), gradually all the way to someone like Schoenberg, who experimented with the 12 tones of the chromatic scale in a purely analytical way, completed removed from any religious context.
All this history might not seem significant, but what seems important to me here is that the way to
interface with what I'll here call creative expression (rather than "art", provisionally), has shifted in step with the shift from a sacred to a secular world. In other words, there's been a shift of emphasis from
what is expressed to
how it's expressed; a shift away from function and towards form. Conceptual art was the logical conclusion of this shift, but it's already past it's peak, culturally.
I see no reason not to assume that creative expression will continue to shift in step with how the world changes philosophically. For instance, amongst us millennials (to my constant chagrin), how we think about and use creative expression has shifted to the concept of a person being a "creative". A "creative", as an individual person, in our parlance, is someone who uses creativity generally for a capitalistic purpose (advertising, tech start ups, branding, graphic design for corporations etc), rather than to express what we would, in every day usage, consider artistic: something expressed for it's own sake, and not specifically for profit. Even popular music largely falls under the branch of something made by a "creative" rather than an artist, although maybe it's not there yet linguistically; however, the need for artists to increasingly market themselves at higher and higher levels on increasingly transient social media platforms squarely places them, functionally, within the same class as "creatives" who work for corporations, rather than artists.
Eh. A rant from a disillusioned artist.