* Diaspora will fail because it sounds similar to something someone else tried one time that failed.
* Nobody will use Diaspora because it will fail.
* Diaspora will fail because nobody will use it.
* Nobody will use Diaspora because it will never ship.
* Nobody will want to pay for Diaspora because nobody will want to pay for it.
* Diaspora will fail because the creators are young.
I don't know whether or not Diaspora will succeed. The old school cypherpunk in me wants to see Diaspora, or something similar, succeed. I would be more curious to see a well reasoned article on the obstacles Diaspora has to face with getting traction, and finding a viable business model.