Oh well… it will be over soon enough, give or take a few million years! And then we can do it all over again… 
There comes a time when, after a very long period has passed, this cosmos contracts. As the cosmos contracts, sentient beings are mostly headed for the realm of streaming radiance. There they are mind-made, feeding on rapture, self-luminous, moving through the sky, steadily glorious, and they remain like that for a very long time.
DN1
Bhikkhus, this saṃsara is without discoverable beginning. A first point is not discerned of beings roaming and wandering on hindered by ignorance and fettered by craving.
…
There comes a time, bhikkhus, when the great earth burns up and perishes and no longer exists, but still, I say, there is no making an end of suffering for those beings roaming and wandering on hindered by ignorance and fettered by craving.
SN22.99