It’s pretty much a certainty that we won’t have any living descendants in 250 million years since no large species ever survive that long. Our own ancestors 69 million years ago were at best mouse-sized.

Unless: we develop some sort of propulsive technology that can accelerate us to very near the speed of light. It’s possible we could still be around because of relativistic effects. Poul Anderson wrote a book called Tau Ceti where a spaceship that uses interstellar hydrogen for fuel gets stuck endlessly accelerating and ends up outlasting the collapse of the universe, only being able to slow down and locate a planet to settle on in the next universal cycle.