For an example of where this is going to end up ultimately, you only have to see what happened when Vince McMahon bought WCW. Sure, there's a few money fights, but then what? I loathe UFC, but love PRIDE. This sale depresses me, if for no other reason than an American company now owns a Japanese MMA promoton. We're a minority, but there are quite a few fans who see this as a bad thing.
For an example of where this is going to end up ultimately, you only have to see what happened when Vince McMahon bought WCW. That's a bit different. The quality of the product was dependent on writers and actors, so if there is only one group of actors and writers, there can be only one product (good or bad). Newer, better "actors" didn't necessarily replace established bad "actors", and the same with writers. In true competitive sports, the quality of the product is based on the skill of the competitors. If you bring the "best of the best" under one roof, it should produce the best product (fights). Better fighters will rise to the top and the bad ones will get knocked out (figuratively and literally). Smaller MMA promotions will still exist (locality-based ones and successful traveling ones), but they'll either grow to be competitive with Pride/UFC, or act as a funnel of talent for "the majors". Either way, it works out well for everyone.
This is the best sporting news I have heard in a while, more victims for the Iceman! I can't wait, just like BI said above, this is going to be awesome!