Regarding content, I could see it going both ways. If they drop content frequently I'm definitely going to keep playing. It's just a matter of how frequent content is released and how substantial it is. I really want them to deliver, because I'm enjoying the hell out of this game.
I think you dudes who hit 50 in literally like 3 days are not going to be happy either way, because it sounds like you have more time to play than they have content right now. I'm sure the rest of us will get there in a few weeks, but I just plan to take a break for a month or two and check out 2.1 if I get bored. Most games launch with poor endgames, they build it up over multiple content patches. Maybe check back when 2.1 hits if you're really unhappy with the state of the endgame. I think the rest of us are taking it a bit slower and casually. I just imagine I would hate even the best of games if I was putting in 8-12+ hours a day or whatever.
I think it is a concern though, I hear what you're saying. How frequently are content patches planned, and when is the first? They really are going to need it in the long run to justify the subscription, I think.
