Yeah outside someones appeal for European leagues I'm not sure what the draw would be to replicate it in North American sports. In my opinion it works better when you have a bunch of smaller national leagues, rather than a large continental super league.
Though with the NHL pushing towards 36 teams now, and considering how long teams sit on the outside of the playoffs already, just thinking about it for a minute here I could see a setup that almost works. Keep the 4 divisions, but split the league in two. A higher salary cap 20 team pro league, and a lower salary cap 16 team draft league. High cap league has the regular 16 team playoffs, with the 4 divisional teams that don't make it relegated. Low cap draft league ends with divisional playoffs, the 4 division winners getting promoted.
The general benefit here is you ease the salary cap burden for teams in 'rebuilding' phase, but it's going to cause all sorts of problems on the PA side.