At this point, I can't see too many campaign worlds popping into the scene unless they are either fantastic, unique, or an old campaign being updated to the d20 system. Maybe I'm wrong but...
Dragonstar: Pretty different right?
Iron Kingdoms: Ditto
Scarred Lands: Ditto
Erde: Still looking through
Arcansis: Still lookingthrough
Fading Suns: non-d20 originally
Harn: non-d20 originally
Deadlands: non-d20 originally
Forgotten Realms
Greyhawk (apparently dead again outside RPGA)
Most other settings, like Karathis (fiery dragon) aren't integral to the modules so I wouldn't even countthem as settings. What's the setting for the basic core WotC modules? Probably Greyhawk, but like the Necromancer modules, they can fit pretty mcuh anywhere.
I hope that more material like the Encylopedia Series, and the Arcana series flourish where it can be put into any setting.