How will the environment in the future be different from what it is currently? In what ways are the current anatomy and physiology of humans, squirrels, etc. insufficient to deal with these future environmental changes? If there are no environmental changes that a species can't deal with, then there's no selection pressure and therefore no major changes to a species. If there is a selection pressure, then the nature of that pressure must be known in order to determine the result of evolution of that species.
Evolutionists have hundreds of millions of years to study the patterns of the evolution of species and apply this to the future. C'mon, it works both ways, what's my cousin the snail going to be when he is no longer a snail. He's going to have to be something!
Even knowing the changing selection pressure, you don't know how a species will respond. It might just go extinct.