Yes, I see where you're coming from. Let me refine my point. Niches will probably get smaller and smaller. Facebook may lose market-power to smaller, more focused networks. I'm just not sure if that will weaken Facebook to the point that Facebook stops being "the" social network. Facebook is still the ultimate place for global connectivity. Perhaps Facebook will remain Facebook, but people will stop using it as their main social outlet.

Like you said, this could result in dominant players within a vertical space. But, how large will these vertical spaces be? I don't know. If i knew, I'd be a millionaire. (I'm not.)

Thanks for the mind candy though.