Tech moves so fast, I can’t think of a termination event that couldn’t be solved with 1M years of exponential growth.
Even with the Big Freeze or Big Crunch of the universe, there’s at least some hope that some currently unknown science, energy source, etc. might be accessible to us in 1M years that could delay or reduce the severity of the event.
But, let’s say there’s a an event that will somehow destroy our entire solar system in 500 years, that would certainly divide people into two camps: one hell bent on escaping the solar system at all costs and another determined to enjoy every last moment before extinction.