Carsland won't be coming to WDW anytime soon, probably not ever. The word on the street is that they want to keep Carsland a DCA exclusive. They didn't do Indy in WDW, but went with the Dinosaur ride which is a very similar ride system, hence no Indy. Plus, Epcot has Test Track, historically they don't want rides that have too similar a ride mechanism.
Avatarland is stuck in development, but they obviously need to add something to Animal Kingdom. They aren't going to creep along with Avatar, plus also look at cloning Carsland. And, they did a Radiator Springs themed hotel, which would look very awkward if they did Carsland.
Indy is a great ride in DL, but let's face it, the Indy franchise sort of hit a bump in the road with the last film, the series really hit its peak over a decade ago, so why would they clone Indy for WDW? The headlines would make Disney look a little out of date considering Transformers and Potterland.
You gotta take everything that has been said about Carsland with a grain of salt as it is mostly fans going to Carsland and then concluding that it will come to WDW. Indy . . . if they were going to clone this ride for WDW, the opportune moment passed a long time ago.
Funny how the rumor involves two things that DLR has that fanbois in WDW want cloned!