Awesome list! I hadn't heard of some of these. At a cursory glance it appears more of the same. I don't think I need a crypo currency when I post a picture of my dog to share with friends. I'll do more research on current alternatives but from what I've seen they don't seem to offer the basic functionality of Facebook. Maybe I'm over simplifying the concept but wasn't the idea of Facebook just a website to share stuff with friends and family?

Enhancing an existing alternative is interesting. Do you think it would be a matter of contributing to some of the current open source alternatives?