It would take more than thousands, even hundreds of thousands of years to produce even a subtle evolutionary change, much less a quantum leap like that. I respectfully think you mean eons, not millenia. I may be wrong. "Millenia" may be a blanket term.
Most importantly, it's an overly optimistic and generous suggestion to say that humans will be around for another 500 years, much less even a thousand. Thus, the evolutionary chain of ascent would break forever.
If I humor you, they probably wouldn't argue about such a thing. They'd know for a fact that they're our descendants and wouldn't have silly hindrances like religion or pride to taint the truth/their reason. I mean, if they survived our destructive legacy, then they ain't no slouches in the thinkin' department! lol Plus, they'd be more sophisticated than us, so...
