I think there always will be "dominant groups", as long as being in group is more beneficial than not being in one - simply because even an uniform random distribution is not perfectly uniform when you build it point by point.
A dominant group is not one that is merely more beneficial. If there's a rat park somewhere that has happiness level 5, and the other rat park has happiness level 6, that doesn't mean one is dominant over the other. It just means one has more happiness than the other. And in an effort to not cause too many paperclip maximizers, let's define some acceptable margin of difference at which it doesn't really matter who's happier, I don't think the world will explode and the philosophical arguments are seriously not worth it.
Dominance is something else entirely and I staunchly disagree that this strictly evolutionary construct needs to persist forever.
