I'm going to use an expression my father used today when talking to me about the Canucks--

"I don't want to sound like a homer, but..." I am optimistic about the chances for Green Lantern getting a sequel. I think with Superman Returns, it suited the interests of the suits at the time to say that it was a failure--when it wasn't--so they could pursue a different direction (and leave all the people they made commitments to in the lurch). Green Lantern will perform at about the same level as SR (and Batman Begins), but the execs will say it performed according to their expectations and they will go into production for a new movie. 

They already made commitments to Ryan Reynolds and Blake Lively for a second movie--and I expect to see those actors back, as well as Mark Strong. All three of these actors did the job they were hired to do. And I'm sure it's in WBs best interests to stay on good terms with Reynolds and Lively. They are already geared up with the CGI from this movie for the next one.

They might fire a few people, they might hire new writers and a new director, but they'll continue to build this franchise. 

Really, what else can they do? They have to keep trying to build on what they've got. They can't just keep relying on Batman.