Aldarc
Legend
I would put Nentir Vale in the "A Snowball's Chance" category since it wasn't even listed as a setting in WotC's recent survey. It also shares its Dawn War pantheon with Exandria, and I suspect there would be some ignorant fans who would accuse the Nentir Vale of ripping off Exandria's lore.If the "three classic settings will be attended to" holds to be true, as far as legacy settings, I think they fall into the following groups:
Top contenders: Dark Sun, Planescape, Greyhawk, Ravenloft, Spelljammer
Unlikely, But Maybe...: Mystara, Council of Wyrms, Dragonlance*, Al-Qadim, Birthright, Nentir Vale
A Snowball's Chance: Jakandor, Hollow World, Blackmoor, Kara-Tur*, Maztica*, Ghostwalk