I guess you missed DC/WB's list of upcoming DC films? They have a whole slew of them planned after BvS. I agree with you, but they do have a schedule it seems, whether they'll fulfill it or not is up in the air.
For 20 years people said that Nicholson Joker would never be topped and that there shouldn't be a new Joker. Ledger came along and everyone hated the idea, the love for Nicholson was even stronger. Then, Ledger blew everyone away. If BvS is a success and the solo movies planned for Affleck Batman come to fruition, you can bet there will be a new Joker by a new actor. Sure, people will ***** and moan "but Heath was teh best", but that didn't stop them from the jump between Nicholson and Ledger.
As for dolls, I don't think anyone really cares. Ledger Joker sells? There's a demand to meet? Then explain that Bank Robber Joker that's not selling on Sideshow. It's been warming their inventory for months? The Donner Superman and Burton Batman films used to be hailed as "teh greats" with their "top 10 box office draws" and they got swept away so to speak (even though there's been a revival). Nolan Batman and the Avengers aren't even a decade old yet, it's only a matter of time before they're ancient history. I remember when Raimi Spider-Man was a big deal for years, look what happened with that.
If what you say is true, what the hell happened with James Cameron's Avatar? That was a big deal a few years ago right? Huge box office draw then . . . . it was over. Nobody really cares. The merch doesn't sell, nobody really talks about it, it just sort of faded away.