While I'm sure this scenario would be the wet dream of some people on this board, there are many differences between the DCI system and the deal XJet has set up.
First of all, for ASA and/or Comair to be of any value to any potential buyer (IPO or otherwise), there would have to be some exclusivitity associated with it. Remember that XJet is the only RJ provider for Continental for another couple years, and they've already had a few years of that arrangement. Why would anybody bother with ASA or Comair if a year after they were sold (or raffled off, whatever) the powers that be at Delta decide that they don't need their services anymore?
This also isn't the same environment as it was when XJet was spun off. Even a few years ago 50-seat RJ flying seemed almost unlimited. Now there are few avenues for growth, and for every regional that is expanding, there is another with doubts about the future. If even one moderate-sized regional were to lose its codeshare, the flood of almost-new RJs on the market would significantly devalue any potential that the spun-off regional would have.
Not to mention that XJet has no peer in terms of Continental RJ flying. Even if in 2007 CO put out a bid to replace all of XJet's flying, or even to do certain sections of it cheaper, who could come up with that many jets overnight? Of course if Delta wanted ASA out of the picture they already have 3 other connection carriers in the system that could absorb that much quicker.
Of course, if Comair was spun off, other regionals would have to start worrying as they have the lowest costs in the DCI system. And ASA, with the George & John philosophy still lingering behind about spending as little money as possible to get the job done, can't be very far behind.
My uninformed opinion was that if this was really needed, it would have been done by now. GG is saying that he's looking at the possibility because the stockholders would revolt if he didn't at least consider it. However, I don't believe he'll actually pull the trigger.