You just might have something there, Jock. In the event CBS is interested in making CKG a viable frequency again, that would solve the problem. So here's how it could go down:
CBS either doesn't renew Mike North from WSCR when his current contract is up, either sending him to WFAN or letting him go all together. They move Steve Dahl to replace North on WSCR, forcing him to go back to mornings. CKG moves Garry Meier up to their morning show, and that opens the rest of their day for "Fresh" music.
What CBS in Chicago "saves" on Mike North would probably cover personalties for the other dayparts, since the music would be the thing.
Another way to make this happen would be for CKG to let Dahl go elsewhere, and then return to WLUP in order to stay on afternoons.
Only thing getting in the way is that something like this makes too much sense.