Even if you adapt toward peace, the transhumanist with the giant robot dong might have a reproductive advantage over the guy who opts not to be modified (I am making some pretty broad assumptions about the desires of women, but I think that history will bear them out, and anyway, this is just an example).

That said, I don't think maeon3's "genetic transhumanism" view of the future is terribly plausible. Modifying ourselves? Already started. Flexible genetic modifications that can do things like giving us magic laser-scatter-vision? Not plausible.