Well, if the Red Skull truly isn't coming back then they might rework Crossbones as something of a fanatical successor. That, of course, would likely draw comparison's to Nolan's version of Bane taking over for Ra's (and it wouldn't help that the two characters look very similar). But that could be the direction they're headed.
Also, check out the trailer to Lay the Favorite. Grillo is in it briefly, and he's already looks JACKED.
Michael Shannon for the Man in the Yellow Hat