ISPs hosted email servers for individuals for years. I don't know why hosting a social networking server for Customers would be any different. I don't know enough about the tent.io API to decide how I feel about it, but I think that history with SMTP, NNTP, etc, shows that decentralized protocols with servers hosted by a diversity of third-parties (instead of a single Facebook, Google+, etc) can work.
I would think ISPs would love to host folk's social network servers. Just think of all the social data they'd have at their disposal for whatever they could use it for.
