Sales will never tank. It's not even worth a passing thought.
Diehards have been jumping off for a decade now. Any hit whatsoever on EAs bottom line? No, because soccer mom's and grandparents take our place in line because their kid has to have the game.
They have a guaranteed audience, not just due to the exclusive license. They get alot of things right. MUT is an absolute runaway hit and for the moment, a huge cashcow.
I'm not defending them. The product is clearly not what the old guard is looking for. Our hopes for the product we want rest on 2k, or MS. Or hell, maybe Rockstar decides to turn the world on its ear.
.. my opinion, anyway.