I have to wonder if they're saying 'using the 1dIV AF system' is just an easier way of saying you aren't getting 61 points like the 1dx.
And lets be real here, someone mentioned an absurdly low price, like, $500 less the the current new price of the 5dmkii - Canon is already proving people are and willing to spend $2500 on a 3+ year old body with a crappy AF system. Following that logic, even if all they did was an upgrade to a 7D like AF system, with better weather sealing, that alone would justify a more than the current model starting price. And if it does have higher ISO, better DR, then yeah, you have a $3000 body, one that has enough upgrades to make it worth it, but, doesn't undercut the 1dx.