This is actually a chain reaction. Continental, anticipating its entrance into the Star Alliance, opted to move its gates over to be with United in Terminal 1. United's rapid shrinking opened up some gates over there for its new partner. That meant Continental would leave its gates in Terminal 2.
Northwest is already located in Terminal 2, but Delta was over at the far end of Terminal 3 with six gates. Delta decided to take over Continental's gates in Terminal 2 so it could combine its operations with Northwest. That is what has been announced for November 3.
So what happens to those six gates in Terminal 3? Well Delta is still on the hook for them, but they won't be using them. So you have to imagine that the wolves are getting ready to pounce.
The rest of Terminal 3 is American Airlines territory, and they've expressed an interest in acquiring those gates for expansion purposes. It would make sense, of course, but that doesn't mean it's a done deal.
Virgin America has publicly announced it wants to fly to O'Hare but it can't get gates. (Actually, it just can't get gates that it wants or that it's willing to pay for.) So this could be their chance to get in there, if they're willing to pay the price. I'm sure there will be a lot of fascinating discussions behind-the-scenes, and I can't wait to hear how this plays out.