I don't think this is really centralization. Just another avenue for advertising. For example, even if (less mainstream) bands generally use a Myspace URL as their web presence, Myspace doesn't necessarily control the music industry.
I find the Facebook-controlled universal login much more unsettling, personally.
I wouldn't expect failure unless people are extolling the almost certain exponential growth of user base. Where are the numbers on stagnant users? I have 4 very close friends that I would rather update via email or IM simply because I don't really care for the opinions of some people on my friends list and keeping track of that is a waste of time.
