But seriously, Holocene, that is what life is all about, isn't it?
We can't ever say anything definite about the future----the Earth could be swallowed by a black hole or pulverized by a collision----life and evolution could simply end.
But if it doesn't end----if evolution continues----then isn't it reasonable to expect other species eventually to take the lead?
It might not be squirrels

, it might be robots (if they get so they can reproduce) or corporate entities (analogous to hives, flocks of birds, antheaps, perhaps involving several biological and machine species). One should be prepared for surprises.
It might be something like a human, but a different species from us created by genetic engineering.
If conditions on the planet become unfavorable to what we think of as higher forms, then some microorganisms might become predominant-----or let's say a giant fungus which has acquired the ability to consume plastic and aluminum beercans and which also constantly synthesizes and disperses viruses toxic to other types of organism, if any are still around.
Holocene, I suspect YOU of having some notions about the future course of evolution. Why don't you tell us your ideas.
Anyway the direct answer to the question Won't everything collapse? is, I think, yes obviously it will.
In the meanwhile I hope that humans succeed in extending earth-type life to a few exoplanets, so the game can be played out in different ways under different circumstances, each endlessly varying and utterly fascinating.