Whatever you think of "moving beyond matter as a computing substrate" (which has been the subject of far more serious sci-fi), it's not implausible that our AI descendants could decide to leave. In fact, "mostly indifferent" volitional AI seems more plausible to me than "good" or "evil" AI. And von Neumann probes could rapidly (within a generation) produce more offworld compute capacity than could ever be safely operated on-planet.