Say this rumor of a third Nolanverse film is true. Here's my thoughts on potential villians:
-Phantasm for the love of god Phantasm. Also solve the love interest for the film too. And she needs to come out of DCAUverse (not that it isn't an awesome universe, but she's too awesome for just one continuity). But she's not an instigator, so she'd have to be in the employ of a more far-reaching villian.
-Talia would be quite welcome considering that Ra's (whoever he was) was supposedly killed off in the first one.
-I know everyone wants Riddler, but honestly I don't think he's enough of a force to carry a movie by himself. There'd have to be more powerful villians around him, mostly in the way of physical power, which brings me to
-Bane would be interesting to see in a more real-world style, given that all they'd have to do is make his steroid seem plausable. It seems simple, but they'd have to do it in such a way where people wouldn't be all "no it doesn't work like that".
-Catwoman would be a bold choice, but there's only so much you can do with her insofar as storyline. Augmenting a bigger plot would where she'd shine most.
-Harley is almost certainly a flat-out no. The only way I can think of that they'd bring her in is if there was some sort of Joker cult rising. Of course, if it was up to me I'd just recast Joker but apparently the fans would riot in the streets if they did that.
-Penguin, as probably the most realistic standard rotation villian they have, would be quite simple to slip into the mob subplot. Especially since he wouldn't have been subject to the fear toxin since he's never been to Arkham (he goes to Blackgate--he's not insane, just a criminal. Although if they wanted to go that route, he could have been visiting someone, I suppose, given that the first film had a boss fake insanity to get out of prison).
-Ivy would be have to be massively reworked since she's one of the most unrealistic characters, and as a standard ecoterrorist she wouldn't be able to carry a film.
-Freeze would be doable. I know people tend to put him in the same boat as Ivy because of elemental control, but his is weapon-based compared to her inherent ability, and weapons can be explained.
-For that matter, Firefly is also weapon-based. Plus they'd get to blow shit up constantly. But he also doesn't have the ability to carry a film. He'd show up, get smacked down by someone, and the film would go on without him.
-Black Mask is another person I can see being put in the mob plot, especially coming as he does with his masked associates. Be enough for a subplot in and of himself.
-Mad Hatter would make for an interesting successor to Scarecrow's reign of mind control, only more direct. But they'd probably have to drop the Alice addiction, or at least lessen it to a few references.
Basically, out of all of these, the only ones I can see being strong enough to be the real LEAD villian are Penguin, Freeze, and Talia. Possibly Hatter if they make him enough of a mastermind.
And give us Matches Malone! We need to see him!
Now I'd like to hear what you think!