I guess I got into the smash scene because of Brawl. When Brawl's release was coming up I picked up Melee again the summer before, got really competitive with it for a few months up until Brawl's release, played it for a while, decided I couldn't play Brawl without screwing up my Melee game, and went back to Melee for a while. At that point, I was still fairly serious about smash and really did want to get better, and I attended mainland tournaments and smashfests when I could. I still entered Brawl tournaments, but never took it seriously. I like Brawl (though I like Melee more), but the moment I take it too seriously it becomes a lot less fun for me.
Fast forward a few months and now I feel like I peaked a while ago and I'm just not getting any better, in Melee or Brawl. (maybe that's why I've been playing a lot of 64 lately and having the most fun with it?) It's more of a personal mindset than anything; I just don't really have the urge to practice and get better and I'm fairly busy with school and other priorities, but I still play the game a lot, mostly at Victoria's smash nights. Don't get me wrong, I still love smash and I'll probably keep playing it for a while longer, but as paradoxical as it sounds, I've pretty much become a casual competitive player. I play by tournament rules and I still enter tournaments, and I do alright and I don't care. I personally have a lot more fun when there's nothing huge on the line. Heck, the reason I started smashing competitively started with a ton of Melee friendlies against my brother almost every day for that first summer (Doc vs. Pika all day long), well before I knew how to wavedash or l-cancel or got into any smash community.
Even in this case, I still haven't quit completely mainly because I <3 the community so much, especially the Victoria community. Everyone generally gets along, there isn't a huge amount of drama that goes on (save for big things that need to get resolved quickly), we have a decent skill base for smash (though nothing compared to the mainland), new people seem to keep coming in at the start of every term (at the end of last summer we had about 7 smashers, now our meetings get on average at least 10 people every week, I think) and overall we just have a great group of guys. I've made so many new friends just because we all share the same gaming passion, and we all have a great time. I don't really go so much anymore for the game (heck, I've played more SF3 and SF4 at smash nights than smash itself), but more for the people there, and it's awesome. I wouldn't have it any other way.
Wow, long winded post that went kinda off topic. That's my situation, though. TL;DR: Yeah, I guess Brawl got me into smash. But it's gonna take a lot more than Brawl getting boring to make me quit smash.