So, obviously, Ben Affleck is going to be in some solo Batman films somewhere along the line when he isn't busy turning up in all the other DC movies because of editorial insecurity.
But who is going to be the villain? This is a very, very important thing, perhaps more important here than in any other superhero franchise. You see, the problem is, and there's no way to put this gently... Batman is very, very boring. The character is basically immune to character development; he can't go more than two hours without a recap of his incredibly famous origin; and, if you let a general audience think about his actions for too long they might question why the hero of this story is a very rich person beating up very poor people instead of seeking treatment for his obvious PTSD or using his massive wealth to do any actual good in the world.
Who, though? The Joker, Catwoman, Bane and Two-Face have all had two films each; Penguin, Riddler, Poison Ivy, Ra's al Ghul and Talia have scored a film; and, Scarecrow jobbed his way through the entire Nolan trilogy.
Who does this leave? To me, there is only one choice, and not only because this will bring further torment to my non-comic fan best friend's life.
The Condiment King! Complete with ketchup and mustard guns!