if humans have survived for some hundreds of thousands of years on this earth, in a more primitive form than what we have evolved to now, i doubt they're all going to die at the end of 9999. they're certainly going to have evolved somewhat from our current state, but dead, i don't think so.
physically, i'm afraid that's impossible. but who knows, there might be a point, when both of our physical lives on this earth is over, that we're able to re-unite spiritually. and you know that spirits seem to last forever.