I'm actually relatively optimistic about Strikeforce.
EliteXC fell apart for a number of reasons. One of the main ones was when they bought several of the lower level orgs (including their debt) which came to millions of dollars. Further, they opened the cheque-books for the Orgs to bring in top fighters. Now as a fan I was far from upset that Cage Rage got to bring Vitor, Ninja, Sperry, Imanari, Shaolin and Fickett, but they don't come cheap... and attendance didn't really go up. Likewise EliteXC apparently spent over $3m on their website and 10's of millions on a lavish headquaters and apparently had a very bloated organisation. They wasted a whole lot of money, and were nearly entirely dependant on getting good ratings for their CBS shows. This in turn came down to Kimbo... the difference in the ratings between the shows he fought in and those he didn't was huge. Having him lose, then the controversy over possible match fixing and EliteXC's creditors suddenly weren't so happy and recalled their debt.
Scott Coker and Strikeforce have been the picture of responsibility, a direct contrast. They have never come out with the big "We're going to crush the UFC" comments others have, because they're smart enough to realise they couldn't. They became a regional power, main based around San Jose, concentrating on building local ticket attractions and putting on interesting bouts. Everything they've done so far has been responsible and nearly risk free. I don't expect them to suddenly jump out there, but I expect them to slowly and surely build themselves as a real consistant alternative to the UFC in the US.
A lot of people also forget the good EliteXC did... notably the ShoXC: Elite Challenger series which had some of the best match-making of any org I've seen and gave great exposure to unknown fighters.