I think we see reality TV shows have a more limited life span than "good" scripted shows.
With that said, TUF does have one advantage over the "regular" reality shows:
It's fan base.
Sure. People get bored of watching people eat bugs on an island or backstab each other to try and get a job. But after awhile it gets stale.
But people who love MMA or combat sports in general, will keep watching because we like to see who is the best fighter.
I never "tuned in" to see what those crazy wacky kids were gonna' do next... "...who will put shaving cream in who's bed this week?..." or "...who will draw a mustache with a sharpie on the back of somebody's bald head?..."
That's not why we watch.
We watch to see our enemies driven before us and hear the lamentation of the women.
So, it will continue for awhile... until more shows come on TV based on MMA (it will happen... Showtime soon, HBO soon, friggen' MSNBC has Warrior Nation for chris' sake!) Then it will fade.
But for now, it's hear to stay.
They are doing the LW now,
then will come another season of HW probably
then the "regain the title" with only UFC guys who had the title
then the midgets
then the donkeys
then the losers have to sleep outside in a tent
"Less is more." - MVDR