That's an interesting thought.

I think it would depend on marketing propaganda still being in play or not. I think if it is, then it would be quite disastrous. Bodies would become even more extreme and following the whims of fashion than they do now. Those who couldn't afford the procedures would suffer terrible psychological stress. It would further entrench economic castes. Also, everyone would look the same.

If advertising were done away with however, and we've gotten to a point where all bodies were more accepted and acceptable then I think people would stay more or less the same as they are naturally. Enhancements would be modest. There would be more extreme conversions but that would be for people with genuine body dysmorphia or maybe occupational reasons (like extending your finger length if you're a concert piano player or shortening your stature if you're a fighter pilot) or sports advantage, that kind of thing.

When you get beyond the idea of aesthetics, then the idea of body modification gets really interesting. What if instead of terraforming Mars to suit humans, we altered humans to make them suitable for Mars by recombining human generic code with plants so that humans can breathe CO2 and expire O2? Obviously, there would.be more to it than that, adjustments to compensate for different gravity effects, for example.

Sooner or later, we're going to start modifying our own genes large scale. It will be interesting to see, for sure.