Diaspora will be fine, now it's on Github it has so many skilled eyes on it. All they need to do is deal with the flood of pull requests effectively. A lot of people want this to win. A lot of hackers will commit code to it because it's a project with the world's eyes on. I wouldn't be surprised if Facebook picked up a few people who commit really good code to it either.
If anyone thinks that, they would be best served talking to the Joomla or Drupal (or any other popular, large-scale, user-facing, and general purpose open source project out there) and get their perspective on how that actually works out in reality.
I know we have this sense that open source software development is one big happy stone soup where everybody pitches in, but at some point, people have to make architectural and system design decisions and map out a direction in order to make any sense of those changes.
In other words, "many eyeballs" don't make all bugs shallow, they make them more noticeable. Which in Diaspora's case, is more of a problem than a benefit.
In theory, this is great, but it's really hard to do actual work while wading through 6 separate reports of "It says the db can't connect to this host and port, what do? Derp!" The mailing list is even worse.
It's really hard to separate real, actual issues from a few hundred people who don't know how to run a ruby-based website.
Even the people that seem to know enough to help fix bugs are stuck arguing about whitespace and license choice. That's a waste of time both for them and the diaspora time when there are clearly bigger issues to solve.