I mean, I understand that there are a lot of reasons why someone might drift away from the fandom: people’s interests change and many folks just don’t stay with one fandom for a long time; and there are only a half-season’s worth of episodes and one movie so maybe that’s not enough to sustain someone’s interest in a fandom.
I, too, have a few fandoms that I’m not as gung-ho over as I once was. But I’ve been a Browncoat for a while now and I love how active and vibrant the fandom is -- as soon as I got into the fandom, I knew I’d be with it for a long time. There’s a wealth of fanfic, fanart, fan discussion, conventions, etc. We Browncoats really try hard to keep the fandom going.