And to wrap up this long answer, I've found each fandom you make friends who stick and eventually you'll share a fandom again because a show that has the same qualities as the one you met in will pop up and there you'll both be.

I think you've nailed it and given me hope at the same time. Of course the shows we end up fanning appeal to a particular audience type and so you'll find a lot of the same people coming around. I guess the migration from the stargate fandoms to supernatural is proof of the pudding... :D