The thought crossed my mind to have it be the Leafs moving instead of Columbus.
And from looking at the handy graphic NHL.com put together:
http://deadspin.com/nhl-realignment-in-one-handy-graphic-453714872
Seeing it visually colored out... it's even simpler.
Move Colorado to the Starbucks Division (Pacific). Move Tampa Bay and Florida to the Caribou (Central). That gives you 16 Western Conference teams. You can move Phoenix anywhere you want geographically West of I-65. In the now vacant Tim Horton's division (Northeast) you have room for two expansion teams. The Dunkin' Donuts (Atlantic) division is left untouched.