I agree with the second point emphatically. I enjoy that the barrier to entry with places like IRC are higher because it's directly correlated with the quality of discussion, in my experience at least.

Regarding the other points, we may well look back at things like Myspace as Halcyon days of somewhat pure Social Media usage. It's a pity we can't still have a social media platform that isn't mined to hell for analytics, ads and GPS stalking but it seems that the tide is turning and people in the Western world are getting over the hype cycle and caring less about being a part of it. Tellingly I had cause to listen to a focus group this week that had privacy concerns about Facebook; before then I assumed it was only the HN crowd who thought that! I look forward to the next 5 years in tech but if I were to lay odds, I wouldn't bet on Facebook weathering well.