You may be right about the Boomers, but honestly how can you be sure that we aren't seeing the same thing right now? Hedonism can be attributed to a lot of the social battles we are currently fighting, with the possible exception of environmentalism.
I think you present a very convincing argument overall, but I think you're presuming that the internet is free of arguments against the Liberal status quo. In fact, I would argue that the past few years have yielded a sharp increase in right-wing online activity. I think this is evident on many of the more Mainstream social media communities. We are always going to see a left bent on the emerging social media platforms due to the user base being young and progressive, but as the platforms become more Mainstream, we will see them shift to a more centrist bent.
Being 36, I have seen this happen in my own little (admittedly anecdotal) microcosm. I work in the advertising industry - albeit in research - and I have been active in Social Media since the turn of the century. I was in grad school as Facebook hit the shelves and came into the working world as it became open to everyone. I witnessed firsthand the blogosphere bubble and I have seen various trends come and go. I have had very high numbers of "friends" - both real and digital - go through years of online activism only to get married, have kids and start sharing blog posts from Momastery.
I don't think either one of us really knows, but it'll be interesting to see it play out in the coming years. Whichever way it goes, I hope it is for the better.