Arizona moves to Quebec .. Quebec joins the Atlantic Div (which would now have 8 teams).
Expand to Seattle and Houston. Houston goes into the Central Div.and Seattle goes into the Pacific Div. Leaving 8 teams in each division in the west.
That leaves the Metro Div with only 7 teams. But, for example, say they expand (again) to Kansas City (for an old rumour's sake) then KC could move into the Central Div in the West. And then you could move Nashville into the Metro Div in the East.
Works geographically in a sense.
In the end:
Atlantic: Toronto, Montreal, Quebec, Ottawa, Buffalo, Boston, Florida, Tampa Bay
Metro: NYR, NYI, NJ, Washington, Columbus, Nashville, Carolina, Phili
Central: Chicago, Minnesota, St Louis, Winnipeg, Kansas City, Houston, Dallas, Colorado
Pacific: Calgary, Vancouver, Edmonton, Seattle, LA, Anaheim, SJ, Vegas
Divisional rivalries could be: Montreal - Quebec; KC - St Louis; Houston - Dallas; Seattle - Vancouver; Nashville - Carolina