I actually got tired of open world (or is that sandbox. Is there a difference?) during the 6th gen and 7th gen had some great entries like Red Dead, GTA 5, Sleeping Dogs. I don't think they'll dominate. In the past, the dominant genres were like space shooters, platforners, fighting games, fps--virtual all genres that can give you a quick fix.
GTA, Watch Dogs, and inFamous are sandbox games where you have complete freedom. Open world games are like Ground Zeroes and Shadow Fall where you're given objectives that have linear gameplay design, but can be approached in different ways... Or something like that.