FR and Eberron are locks. Failure to support either of these two would probably be a financial disaster for the entire edition, as these are pretty much the two main settings (other than homebrew settings).
I could see Dragonlance being supported, as it offsets FR nicely. FR is High Fantasy, while DL is Low Fantasy. However, due to the radical changes to the setting (mostly 5th Age), anyone signing up to be the designer is going to have a hard time with it.
I suspect an Oriental Adventures, but I don't know if it would be Kara-Tur or not. I would bet against full support.
I could see Dark Sun getting support, but it's definitely a maybe. It's got a cult following, and it fits a niche not filled by another setting.
Greyhawk is very iffy. Lots of fans (mostly grognards), but it really doesn't fit a role that isn't filled by either FR or DL. It's Middle Fantasy, but if DL isn't supported, it could become the Low Fantasy setting by default. Also, I have heard rumors that Mearls is a fan of Greyhawk, which could give it the push it needs to reach the finish line.
I don't think Ravenloft, Planescape, or Spelljammer will return as a Setting format. From everything they've said, elements of all three will be included in the default cosmology setup. A Horror module will pretty much then wrap up Ravenloft, so fans of the three settings can use older edition sources to play these settings, but I don't see support beyond this.
Al-Qdim, Birthright, and Mystara are probably resigned to the dustbin of history.