If Diaspora fails, it will have less to do with the awesomeness of the project, and more to do with the lack of everyone's friends actually using Diaspora.

I figure it will be a huge hit among geeks like us, but then will fall out of usage due to the lack of updates from people that matter, like friends and family.

I use Facebook for staying in touch with the mostly non-technical people in my life who actually use Facebook, and that's what will end up swaying most users (like myself) back towards Facebook in a relatively short period of time.