I think us opining on this at this point in time would be like medieval scholars conjecturing about technology a millennia into their future.

My "headcanon" if it's an appropriate term here is that humans will eventually become post-humans and be a cat 5 civilization and we cannot even conceptualize what they might do. Who knows, maybe they'll tame time itself. Or maybe they already did and this is an ancestor simulation. Maybe if they're benevolent enough they'll even let us have an afterlife. Sky is the limit.

I mean, just think on the fact that a couple centuries ago the scientists of the day were concurring that mechanical flight was impossible or that women couldn't ride in a train without damaging their uteruses.