Hello Matt,
The proliferation of social media will not change the fundamental characteristics of a community. Regardless of all the social media out there, community is still a group of people held to gether by a common interest. That is it. Nothing more and nothing less. This has not change for thousands of years. The advent of social media didn't even make a dent in this concept that is very robust in human history.
The different social media channels simply provide the community members with different ways to communicate. If you limit yourself to one platform, then in this narrow view, community may seem to be destablize with the proliferation of social media channel. But if you look at the community holistically. The community still exist, they just become distributed on different channels.
All discussions here are open, so I will only hold the conversation here. Email = Evil and selfish.
Hope this address your questions.