Definitely something different to wake up to and I ended up rambling in a response:
I do agree that LJ is just a fraction of fandom itself. That's the point of the internet in a way - there are no centralized areas for anything. If a site gets pulled down, there's always another one peeps can jump ship to. However, I have noticed that the way LJ works has resulted in a focus on fanworks and multi-fandom interests. People seem to be branching out from single interests (like fanfic OR RPG) to include others (RL posts, fanart, conventions, layouts, fests to celebrate fandom milestones etc.). My favorite thing about LJ, is being able to experience something, write about it and get opinions. And I mean, *anything*. Whether it's RL or fandom, shopping advice or layout design, the community is willing to listen.
There may be other areas on the internet that have bigger fan populations, but when it comes to diversity of content for fans and by the fans, I've never felt as comfortable as I do on LJ. Sure on other blogging sites I can still post up whatever I want, but finding a community that would welcome so many different topics? A bit more difficult IMO.
Then there is the fact that for every post/comment made (for me personally), the time spent lurking and absorbing posts and ideas far outweighs any of it. I recall an f-list post *ages* ago, that talked about lurking stats - and not even on LJ. It was on generally popular and useful sites. Research showed active posters counted for about 1% of the users.
Of course, in RPGs where it's for and by the players, this wouldn't matter. The thing is not everyone is interested in RPG. Not everyone is interested in fanfic. And I do believe LJ is an important part of fandom because it embraces fandom as a whole. Sure there are areas deep underground like file sharing communities or porn comms that are more insular. But seriously? I love LJ 'cause I can find anything here. There may be less of a concentration of any one thing than on other sites (like fic on fanfiction.net) but I don't consider fic, or RPG, or fanart to be the be all and end all of fandom - at least not individually.
Oh and if peeps from LJ were to move to GJ, it doesn't necessarily mean they'll join in the practices of current residents. Look at RL history - migrants set up their own communities and bring their own culture to countries. They'll follow the rules, but changing the way they operate isn't so quick. And I've noticed that countries change just as much through the influx of new people. Seriously? I think it might not be so much of LJ-ers fitting themselves into the current GJ community as it could be the GJ-community getting used to LJ-ers who don't see any need to do things differently- and will create the communities they need when and where they want.
Yeah, that was about it.