I think Canadian football will not fly in the US because it is not American football.
To Americans, football means 11 players, a field that's 100 yards long with 10 yard endzones, fair catches, touchbacks, limited motion and all the rest of the elements of their game. Our game, with all its unique aspects, is just "funny football" to them.
In the 1990s the CFL didnt go to the US because of any great demand for it there, though of course the CFL tried to play that up. In fact, the league went there because they were on the verge of financial disaster and needed the expansion money desperately. It was a fundamentally flawed idea. In addition to issues such as the ratio mentioned above, it was also hard to find suitable stadiums to accommodate the large CFL field, plus officials who could referee our games.
The basic problem then was, and still is, that there is no appetite for Canadian football on a large scale in the US. With the exception of Baltimore, (where fans had recently lost their NFL Colts team in the dead of night to Indianapolis and so were quick to latch on to the CFL Colts, so named initially, before a court injunction forced a name change to Stallions), attendance at CFL games in US cities wasn't just mediocre, it was lousy. I remember reading about games in Shreveport with 8,000 fans, and near the end Las Vegas had 2,500.
I don't see why people expect Americans to adopt a brand of football that is foreign to them in more ways than one. They don't see it as neat or interesting, they see it as basically incorrect. You might engage an American fan in 15 minutes of conversation about the differences in nuance between the two games, but after that short time is up they will lose interest, become bored and return to their own game which they know and love. And why should they do anything else? Their game is pervasively present on TV and at stadiums all over the country, with rabid fans at all levels, and is a game they have known for a century, as we've known ours. There is no sustained room in that saturated market even for alternative pro leagues of US football-- the WFL, USFL, XFL and various other leagues all folded after a time. To think they will ever make room for a different variant of the game that they neither know nor care about is just a pipe dream. It's like trying to make hockey sustainable in Phoenix, Atlanta or Nashville... and we know how badly that is working, even with a league like the NHL which is much wealthier than the CFL.
We have a hard enough time getting back to nine teams in the CFL, and ten is a distant goal. We know the game and have loved it for decades, and we still can't fill 30,000 seat stadiums most of the time. Spending energy on trying to plant Canadian football firmly in the US would be a colossal waste of time. The CFL can't afford to squander its slender resources on a venture that has little or no chance of lasting success.