I signed up for an invite around the time it was announced. It took a while before even an alpha was released. Diaspora has unfortunately stagnated. The future rests with Status.net, Tent.io, or App.net in this field.
You don't need invites - there are many pods with open registration. I'm sure there are many projects that aim for the future. Diaspora is actively developed, which shows that it aims for the future too. Your examples are core technologies, not end user social networks. May be Diaspora will use them as the inner federation mechanism, who knows. There is an on-going effort to redesign Diaspora's federation architecture.
