Not spring. Canon has to milk buyers with the 7D2 for a year or so. If they released 5D4 with 7D2's AF feature in spring (5 months after 7D2 got released (not introduced)), who would buy the 7D2, if the 5D4 offers same or even tweaked AF with slightly lower frame, but better IQ?
I would. I would buy both. As it stands, I'll probably buy a 7DII and a 6D, but if the 5DIV comes out sooner than later, I'd probably buy it over the 6D.