Not a definitive answer, but an estimate untill we get a solid response:
The last several worlds have been opening approximately every 6 weeks with a couple exceptions going up to close to 8 weeks. Therefore I figure the next world ought to open in no less than a week and a half, and no more than 3 weeks or so.
Hopefully we get an official response/announcement at some point soon, and hopefully its a Domination world.