500 years is not a long time in human history terms. Our species has been around for roughly 200,000 years. "Written history" is much shorter but is still more than 5,000 years. So I would guess with utmost certainty that we will still be around 500 years from now. The geopolitical landscape will have changed but humans as a species will be around. Thinking that we live in the ultimate moment of human history is a trait that every human that has ever lived at every time kinda thinks. I mean, technically we (all humans) are currently the most advanced forms in terms of both biology, culture, and technology that has ever existed on this earth.
Also it isn't gone for good but it'll hopefully make a return in the next months but as of now the priority of the engineering/design team is to make the site stable. Once that's done maybe in a year or so they'll bring back achievements and quests.