Let us not forget, however, that the role of Dungeon and Dragon magazines is to (largely) support the core world of D&D and help market new WoC products. If WoC gave up the Greyhawk license so that it was (1) no longer core, and (2) had no new material coming out from them (not like there is any anyway), it would virtually vanish from the pages of Dungeon and Dragon magazines. Now, since Erik Mona is the Editor of Dungeon, would he leave to work on Greyhawk products or stay with the magazine? Who knows. Similarly, with the other Greyhawk savvy staff at Paizo. It could be a bunch of clueless novices end up with the setting in their hands.
Also, many people in the past have argued/shown that it is unprofitable to publish adventures. So, Paizo would likely publish the occasional source book for Greyhawk (like other people did with Ravenloft), but there would be no adventures. Personally, I think adventures MAKE Greyhawk. I would much rather see it remain in the pages of Dungeon where we could continue to get quality adventures.