Almost a single-entity NHL

Wow, Bain Capital Partners and Game Plan pitched buying the NHL and setting it up as a Single Entity. I’ve written before that its possible. The NHL owners would follow the lead of Major League Soccer. Instead of a franchise model like the NFL/MLB/NBA, the league owns all teams and player contracts. It’s even legally testted – MLS owners were challenged in court by some players, led by the NFL(!) Player Association’s own lawyer. Aren’t there other single-entity structured leagues in the US – the AFL maybe?