The one scenario i heard (and the one I like the most) is that Dallas and Colorado switch divisions, Winnipeg would go into the central and the wings would go east.
I don't think Detroit would move. The NHL isn't going to want to break up the rivalries that exist between the Red Wings and the other teams in the conference - it would be like moving either the Yankees or the Red Sox to the National League. My money would be on Columbus moving (they're the easternmost Western Conference team) to the SE division and Winnipeg being in the Central division - basically they swap places. Columbus isn't really "southeast" geographically, but it makes most sense. Maybe the NHL will rename the division to something more fitting.