The NHL has had all these teams in the south for a decade now, some of them even longer, and yet no mega TV contract has materialized. It makes sense in theory, but at the same time if the interest isn't there then it just won't happen.
Also you have to consider the fad aspect. People will be into things that are deemed to be a hot item. If the league as a whole is selling 95-99% of all available tickets, then it's going to garner media attention. The league will be seen as a hot ticket item and potential TV contracts can emerge from that.
I'm not saying relocate all 24 US teams to Canada. I'm simply saying relocate 6 of them. The proportion will still be 18-12 in favour of the US. Future potential expansion areas would be in the US as well, including the unknown market of Las Vegas.