If you mean splitting off the NHL teams to form their own league, then the simple answer is no.
First of all it’s not viable for legal reasons. You can’t just take a franchise out of the NHL and go renegade. The franchise still belongs to the NHL along with its IP (name, logos, etc). So what you would have is an off-brand league like the WHA, games between the Toronto Toros and the Vancouver Blazers. People didn’t want to watch that in the 1970s and they certainly don’t want it now.
Second, it’s not viable for financial reasons. The Canadian teams tend to make a lot of money in the NHL, but that’s partly because they’re in a large and thriving league where they do in fact make money from the American teams. Expansion fees are an obvious example, as well as merchandising and other sources. An all-Canadian league means you’re no longer getting those revenue streams and the pie gets much, much smaller. You don’t have Connor McDavid money or Auston Matthews money in that league, so those guys aren’t gonna be around.
It could be “viable” in the sense that it could be like the old IHL, an off-brand league populated by spare-part players. If they could keep travel costs low, maybe it becomes something like today’s KHL as an option for guys who aren’t quite good enough for the NHL and not a good fit for the A. Its continued existence would depend on finding minor-league arenas to play in, because you bet your ass the NHL would re-activate those seven franchises and push them out of the big arenas.
Would anyone be happy with that outcome? No they would not. So for practical purposes no, it is not viable.