The thing about almost every D&D setting is that they are either a clone of something else (chiefly Tolkien), or don't represent what most people think of first about D&D (Dark Sun, Planescape, and Ravenloft aren't generic fantasy). I'm pretty sure Dragonlance is simply off the table, as it were.
Movie studios want a built-in audience, and as Marvel and DC know well, audience is attached to characters, not setting. What characters does D&D have with an audience big enough to pique a studio's interest? Without Dragonlance they both are in Forgotten Realms: Elminster and Drizzt. Elminster would be rightly seen as a Gandalf knock-off, but no one has put Dark Elves on the big screen before. You'd have to get Salvatore on board and convince a lot of people that a 25 year old AD&D 2nd Edition character can carry a franchise aimed at driving 5th Edition. I think it would be a hard sell all around... would people go to see a Drow movie, or three of them, and still remember that it's D&D?
Because D&D is generic (enough to simulate other properties) it has few unique and compelling character assets of its own. And Hasbro has fucked a lot of shit up with regard to how valuable any of those characters can be outside of game materials.