Oh, come on. The reason we balk at interstellar travel these days is because it'll take thousands of years to get to the nearest star with current propulsion t

Oh, come on. The reason we balk at interstellar travel these days is because it'll take thousands of years to get to the nearest star with current propulsion technology. But thousands of years is still far less than 1B years. If we're still around in several hundred million years and the Earth is getting too hot, and we haven't invented warp drive yet, then of course we're going to build a bunch of generation ships and take our chances in interstellar space. By that point, it really shouldn't be that hard to build such ships that are reliable enough to last indefinitely, powered by fusion reactors.