In the short-term, yes, this absolutely should happen. But for the long-term, all the fighters need to be under one umbrella and Strikeforce, much like the WEC before it, will ultimately outlive its usefulness as a separate promotion, only it'll happen much, much quicker.
Simply put, you want the best fighters under one banner. If you want to talk about bloated rosters and all that, there's a lot of dead weight on both the UFC and Strikeforce rosters. Of course, those fighters have some usefulness, but merging Strikeforce's top talent into the UFC means better fights and deeper cards, which is exactly what we've gotten out of the WEC merger so far. It also gives the company more main event talent to work with and gives the company a whole new crop of fighters to make stars out of.
If the UFC's goal is to have more shows on cable television, or to run multiple shows on the same night in different parts of the world as Dana White has talked about before, then merging the two brands is absolutely critical. Right now, the UFC is high on cards and low on main-event talent. They're in a real tough position. They have done next to nothing to get the featherweight and bantamweight divisions over to the audience and the company's bantamweight title is currently dead in the water, as the fight between Dominick Cruz and Urijah Faber will do next to no business on pay-per-view barring an absolute miracle.
The UFC needs stars or people they'll actually get behind and try to make a star out of. Nick Diaz is a star. Gilbert Melendez can be a star, as can Alistair Overeem. Then you throw in people like Dan Henderson, Muhammed Lawal, Antonio Silva, Gegard Mousasi, Tim Kennedy and the rest, and you have the makings of the best fight promotion the world's ever seen.
Outside of fulfilling a contract, what purpose does Strikeforce serve? If anything, the UFC will only be held back by keeping Strikeforce completely separate. The UFC's middleweight and welterweight divisions desperately need new blood pumped into them and by merging the two companies together, it should, in theory, create an atmosphere of unrivaled competitiveness as fighters will be fighting to prove their worth to the bloated promotion each time out.
There's no doubt this is a big decision that needs to be completely and throughly thought out before any choice is made. As it stands right now, running Strikeforce as a long-term separate promotion will only weaken the UFC and raise the ire of the fans who want to see the best fight the best.