Edited Oct. 19, 2020 at 3:44 p.m.
https://sportleaguemaps.com/hockey/nhl/
I looked at a map and built it from the corners, from scratch, to see if we agreed.
the Southwest is easy: SJ, VGK, LAK, ANA. Check!
The Southeast is easy: NSH, Car, Fla, TBL. Check!
Northwest is obvious: Sea, Van, Edm, Cgy Check!
Then it gets dicier
On I-95 closest to NYC (although, boy this would be a competitive division some years): NYR, NYI, NJD, Bos. Shortest travel in theory, but worst traffic, so it evens out.
Northeast, closer together: Buf, MTL, Ott, Tor
The ones in the middle in the South: Ari, Dal, Col, STL
Great Lakes: Det, Chi, Min, WPG
No shared regional identity, but they're in the middle, and close together, and have some rivalries, now: Phi, Pit, Wsh, and CBJ.
If two teams per division are guaranteed playoff spots each year, the above guarantees at least two Canadian teams make the playoffs every year. Could see swapping Boston and Buffalo over rivalries or over Buffalo wanting to identify as part of New York, but Boston is closer to NYC, and Buffalo is right by Toronto on the actual map.
Obviously if they really want to go with divisions of four teams, some poor intern would have to sit down and google map all six communtes within each proposed version of each division, and add up travel times at rush hour, to see which made the most sense, but just looking at geographic distance on a map, this is my guess for how it shakes out.