And if we are not here ...how will we know....and why do we care?
The fifth chapter of Daniel indicates that there is a reality no further away than the length of a man's arm, which is populated by actual beings who have physical substance of some sort, at least when interacting with our reality. It would be presumptuous to assume that realm is going through the exact same changes and time scales as we in this realm.
As a believer in Jesus Christ and His resurrection, it is evident that the 'laws' of the universe we are bound to in this body do not in fact confine the reality to which Jesus went with His physical body when He left the wrapped burial clothes without unwrapping them and the tomb without rolling away the stone.
If one believes the Apostles' stories, Jesus came from and went to this 'other' realm without difficulty. And oddly enough, this other realm is not even portrayed as Heaven, that's a completely 'other' realm of reality!
BTW, it is clear from the Daniel episode that that other realm is aware of our realm, so the approaching less hospitable to our form of physical existence Universe may be readily discernable to the other realm. In fact, those there may already be able to ‘see’ that future.