To put some perspective on this, I can remember all the panic in 1999 over the coming of 2000. The concern was that because computers could not read 4 digit dates, they would all simultaneously stop working. The result was that all the lights would go out, planes would fall from the sky, banking would fail, traffic lights would stop working and god forbid our nukes (and presumebly everyone else's)would launch, and civilization would be over.

I got up, January one 2000, reported to work, nothing had blown up, no planes fell, no missiles went off, civilization carried on like it always does. No one predict the future because it has not occured, all events are the result of an incalculable amount of decisions being made by billions of people, every day, every minute, every second, which then spawn more decisions, and so on.

So no, no one can say when humanity will end, or even if it will. Change will come, it must, as it is the only true constant in the 'verse. Change is not a bad thing. Without change, there is no progress, without progess, we stagnate and never realize our true potential, which is far greater than we are yet aware.