Still, Gukag, a lot of people do fly nowadays and flight indeed has brought many humans togeter. Perhaps not in the capacity utopists predicted they would do so, but planes have fulfilled their ordained purpose. I believe cybernetic enhancement will do the same - not everybody will have a pair of, say, mechanical legs, just as like not everybody nowadays has a car, a house or the ability to travel around the world, but enough people will do for those enhancements to become an integral part of human culture and alter it in a significant way.
As for your concerns about societal division between the rich and the poor, I would like to say that, having witnessed said division in its most blatant form in Russia, sticking some mechanisms in a rich man will not make him any more different from a poor man than he already is. The rich are already more priveleged and more capable of doing what they want as opposed to what they have to do than the poor, giving them the ability to upgrade their bodies in addition to their cars will not change much. Likewise, the societal division between "haves" and "have nots" already exists and has always existed, except instead of expensive cybernetics it was expensive land, expensive cars, expensive clothing, expensive food and everything else people might want to conspiciously consume. The only thing transhumanist tech will do is bring this division to the surface.
As for "Gattaca", the concerns raised by that film are perfectly valid, but they are less about transhumanism and more about the societal effects of distinct eugenic castes - for what does genetically modifying your babies produce, if not that? Assuming all modifications of his body are performed with a person's choice and consent, the problem depicted should never arise.
EDIT: Goddamn does it feel nice to have an intelligent discussion instead of an endless propagandesque back-and-forth between the opposing sides!