I actually think they aren't going to wait. And we have this out today after Singer's boys shot their mouths off about a definate sequel:
The future of the studio's recent comic book adaptation, 2006's "Superman Returns," is somewhat more dubious. That film cost $209 million (even after various tax rebates) and marketing costs sent expenses upward of $300 million, but director Bryan Singer's Man of Steel picture made only $201 million domestically. While insiders say the movie was profitable, the studio mandated major cost cuts before proceeding with a sequel.
"If we do a sequel to 'Superman,' we want it to be less expensive," Horn acknowledges. "I have to see a screenplay before I say yes to anything. But the studio would be willing to spend as much as $175 million if the screenplay and other factors warranted it."
As someone pointed out in the other thred, "If". I think the WB is laying down the groundwork for passing on it. They know it is going to be a dog, and they have a JLA script they are really happy with, and they need a 2009 or 2010 tentpole, so they need to move on it now.