The Penrose Bounce. If the current matter in the universe turn to photons in the future, the energy of the photons dilutes more and more. The universe will not contain any energy anymore. Time still continues but there is nothing left anymore to create a new universe from. If the universe expands along it will end up in a uniform endless void in which even dark energy has ceased to exist. What could be possible though, is that configurations from a previous universe have leaked into ours, imprinting themselves into the initial contribution of matter and like that ending up in the CMBR. I don't see what gods have to do with this. Even if the universe goes back a zillion, or even infinite big bangs, the the question could be, "who brought the sequence into existence? If you can't answer more closely what the mechanisms of the universe are you can off course say that in the future this will be answered. But that's the easy way out. Take string theory. It is believed to give us the basic constitutes of the universe. Strings, branes, Calabi-Yau manifolds, extra dimensions, a string landscape even, M-theory laws, you name it. The question now becomes: from where these strings, branes, CB manifolds, etc. come frim? If they are the fundaments, there ain't something to explain them. Gödel's incompleteness for physical laws. Only gods can give closure.