The Bain offer (now $3.5 billion) to turn the NHL into a single entity league is intriguing, but will fail for the exact same reason that the NHL is bleeding red ink: owner hubris.
Owners overspend** on talent because they want to win, and want to win big - i.e. to take down the Stanley Cup, or what have you. That's why they bought the team in the first place. They've gotten rich, have money to burn, and burn it on a) purchasing a sports team, and b) paying for player talent. But competition for players makes the latter quite expensive, hence the move towards salary caps in North American leagues. The salary cap is most accurately viewed as a collective policeman: a device to keep the hubris of (N-1) owners from increasing the cost of hubris on the part of the Nth owner.***
Getting a majority of ego-driven men to agree on a league-wide buyout seems unlikely to me. They are in the game for the sport first, the cash second.
There is a scenario I can imagine in which the Bain proposal might fly: if a sufficient number of the fat cat owners are really hurting badly. Some might be Art Modell types. The type whose initial purchase is now dwarfed by the money in the game, need supplementary cash to remain involved, and sell their soul in the process. There might been one or two high-flyers wrecked in the dot-com crash. Or perhaps a corporate group or two (a la Disney) who've been taught a lesson about the economics of owning a sports club. The fact that the sport is temporarily defunct helps too. So there may be a quorom of owners looking for an exit.
If the Bain group has done its homework, and there are enough cash-strapped, disaffected sportsmen among NHL ownership, the proposal has a chance of succeeding. But this would require that a breakaway from the remaining holdouts is feasible, and that some of the glamour clubs be on board. In the absence of that, a single-entity league would get creamed by a rival league willing to pay players what they are worth. The NHL would become akin to MLS, and we'd watch the best players playing elsewhere, as we currently do in soccer.
*I'm late to the party here, but have been prodded by my circle of two readers to comment, so here goes.
** Overspend means relative to a profit-maximizing standard.
***Collective action by owners naturally focuses on keeping the costs from component b) down, in order to raise the costs of component a). In other words, the salary cap is not about controlling costs, per se.