It doesn't have to be final, it just has to be reasonably descriptive of reality.
Even if we review our understanding, the universe is still a massive place and humanity's existence a mere blip. It becomes more about statistics and probability than physics, but yeah, our understanding of physics also makes ETs visiting Earth very unlikely.
If you mean to say "a major revision of physics would make it more feasible", I don't know. Maybe? Or maybe even less feasible! We have to approach this rationally, and so far reason and evidence both lean to "extremely unlikely".
> Let me propose a thought experiment [...] Would you be surprised to learn that relativity, and the limits it imposes, are viewed by those future humans as anachronistic and silly?
As a thought experiment it's a decent piece of science fiction, but as any sort of serious thought it seems like begging the question to me.