it has definitely lost its lustre in north america. do you not remember the amount of hype surrounding the sport in 09? even your random guy off the street knew household names and the biggest upcoming fights. obviously there's some newer fans just discovering it, but the casual fan has all but disappeared.
i agree with this. I have no stats for a nationwide answer to this poll, but the mill I work at is about as 'common' as it gets, and barely anyone talks about it anymore. There were three of us who did before Bonnar-Griffin, then there were hundreds after that fight for a few years, now there's maybe less than a dozen. Also, as a Canadian, the people I now don't talk about GSP anymore or less than other champion fighters. Maybe in Toronto or Montreal he gets people going in a rabid way, but out here he's basically another top fighter who I suppose we root for because he's Canadian, but over the last two years there were a lot of people saying they wouldn't mind seeing him get beat.
My guess is, for the culture around me, the PPV prices drove everyone off, and possibly it was this exciting new thing shoved down (all of) our throats, a new kind of fighting, white guys are pretty good at it, and then it got expensive and no one, upon multiple viewings, is all that excited about it, really, it was just new to them. Hockey trumps it in lunchroom talk by about 1000x's, and actually NFL trumps it by a longshot, too.
People were really excited about Texas Hold'em for a few years, too.....
edit*** - as i think about it, that Griffin fight got everyone into it, and when I think of the fighters that people DO talk about, its the sluggers, the KO'ers, the fancy strikers, etc. The present scoring system which makes it insane for a wrestler NOT to wrestle might actually be killing the sport in my area and peer group.