AACs are not MP4s. So it's not too late to call them that, it's wrong. ;-) Well, MP3s are really MPEG-1 Layer 3 's, so maybe that argument is wrong, too...
No, I don't see Apple licensing "iTunes" that way. Wouldn't be easy, anyway. You'd need a Pentium III or G3 processor in that B&O stereo. ;-)
But I agree that Apple must do something to propagate MPEG-4, AAC and their AAC-DRM. I'm sure they have a plan. They don't _want_ to lose, do they?