I have Administrated many, many forums and sites in the past, a few for considerable lengths of time. I've been doing it enough to know, that in matters like these, there tend to be certain patterns that a community will follow.
In the early stages (pre-release), your community is going to be composed primarily of people who are dedicated to the game. Even if they can't play it, they remain students of it, and often get into numerous deep discussions regarding matters in, of, and around the game. These people will make up the 'core' of a community, and in essence, will define the character of those forums. If people come to a forum and see intelligent discussions going on, they're either going to decide that they want in, or "That's not for me!" and leave. The same thing can be applied to flamey, trolly forums. Some people like that kind of stuff. But all of that is shaped at this point .. things tend to be slow, but very consistent.
When release comes.. you might want to bunker down and brace yourself for the storm. A lot of new people will be finding out about the game .. people who will pick it up off the shelf because online play is free, because it looks cool, or just because a friend said it rocks. They're going to have a lot of questions, and the first place they're going to look is either the official site (thus leading them to fansites) .. or GameFAQs .. *shudders.* What you end up with is a massive influx of people with little experience in that community, and a lot of questions. You'll see the same thing asked a hundred times over, and a lot of behavior that is discordant to what the 'regulars' have become used to. That's not something you can really fault a new person for, mostly .. as it is something akin to getting into a pool. The water is really cold at first, but you adapt. Forums are the same way.. it takes time to adjust, and this is definitely the 'growing pains' stage. You'll often find that a lot of 'older' members will start to act or feel distant, sometimes even becoming bitter. Question threads that used to be answered with a happy emoticon eventually turn to "Read the bloody FAQ" after the Xth time around. That is just the way things go .. it's no different from 'old people' complaining about those 'noisey kids' and their 'crazy rock and roll.' This is certainly one of the most critical points in a forum's life cycle .. if people remain patient, and stress friendliness in their actions .. then slowly but surely, the people that seek questions will find their answers (and not feel rebuked for doing so) which they in turn, can give to the next person that needs them. If everyone manages to survive this stage with their sanity intact, we move along to..
The point where things settle back down. Like a week after a little kid's birthday party, we're not as excited about 'having' new toys, we're kinda used to playing with them now. What this means is that you'll see a focus shift back to the social aspects of the game, something like it was in the 'pre-release' days, only on a much more grandiouse, and more informed scale. This is usually the stage when you notice friends, or groups, or even 'cliques' becoming more visible. Because people now have the opportunity to play as they wish, should they need someone .. where to turn? The people you already know from a forum is a good place to start. Sitting around and talking with someone about something, and actually doing it are two very different things .. and moreso than they would have, people might realize "Hey, so and so is cool." So, things start to take on a more congenial nature. You'll hear people talking about their exploits, or organizing get togethers, things of that nature. Most of the life cycle will happen here.. until..
News of the next Expansion comes .. and we start all over again!
I don't have any doubts for the longevity of this forum, it's just a matter of being an oar in the water .. you're moving with the flow, but you're also directing it.
but you never know).
. hope to see everbody in game though 
I tried.
)
