It seems a bit foolish to dig too far deep into the speculation with so many unknowns at this point in the offseason, but of all the proposed ideas and hypothetical scenarios that have been kicked around, the All-Canadian Division seems to have the most basis behind it.
There are solutions, concessions and/or work-arounds for just about everything, but it is semi-literally a no-fly zone when it comes to the border as long as travel restrictions are in place amid the COVID-19 pandemic. Unless the Canadian government eases its stance on travel and entry, the seven franchises north of the border have no choice but to operate independent from the rest of the league.