I believe that if an NFL team is permanently established in Canada, probably in Toronto, it will mark the beginning of the end for the CFL. I do not want to see this happen and am dead set against the idea.
There is so much hype around the NFL, and so much money, and so much marketing, that in the competition for advertising revenue, media exposure, and corporate support, the CFL will be completely swamped. Without Toronto, the CFL's major sources of corporate support will shrink to a minimal level quickly.
The Argos will fold quickly-- that team has enough trouble attracting a reliable fan base as it is without the presence of a "big league" competitor in town.
After losing Toronto we'd have a seven team league, with Hamilton and Montreal highly vulnerable. I think it would not be viable, or if so strictly as a semi-pro league for Canadian players.
Alternatively, the CFL could officially become a farm league for the NFL. But on that basis there would be no reason for them to want to continue with Canadian rules, which would likely disappear.
I for one would have no interest at all in watching "Triple A" American football, regardless of the location of some teams here in Canada.
I hope none of this happens, but I believe it would in fact be the outcome.
I don't need or want American football in Canada. If Canadian football ends, I'll switch to rugby.