You should remember WotC could publish new worlds, for example ersatzs of Legend of the five rings and Dark Sun.
A Wuxia/Wulin world should arrive after the psionic powers, and at least with playtesting of the martial maneuvers. My opinion is Tome of Battle: Book of the Nine Swords will come back to be used with Oriental Adventures.
Ilkoria has got a special game mechanic, and a d20 version of the "monster pets" needs time, and at least a year of Unearthed Arcana preview. I think Hasbro wants a D&D version of collectable monster franchise (Pokemon, Digimon and like this).
Innistral is possible, but there are many fans who miss Ravenloft. Then we would see a "Heroes of Horror" without links with a setting, a group of modules of Ravenloft, and a guide about Innistrad. Later we would hear some news about media projects, maybe some videogame or teleserie. Let's remember the anime Castlevania in Netflix.
Kaladesh is a world with machines and technology. This needs a lot of playtesting about vehicles and (magic version of?) firearms.