Montreal appears to be a very fickle market. Win and your golden. Lose and you get nothing. Luckily the CFL is a very easy league to win in (unless your Winnipeg for some reason) and it won't take long for Alouettes to get back on their feet. 6 of 9 make playoffs, it relatively easy to get competitive. A 4 year playoffless drought (likely going to 5 this year) is very rare. It won't be long before Montreal is back on their feet though particularly in the weak east division. Once that happens I think it'll be very easy for them to become well supported again. The problem in Montreal is nothing compared to Toronto or Vancouver. Both of which are on going issues.
But again the CFL has literally never been on more stable ground in the past 40 years than right now. The passion in the prairies is amazing (Winnipeg, Saskatchewan, Calgary, Edmonton) with a rejuvenated fanbase in all those locations, despite what detractors will say about all fans being 80, it's not true. Ottawa and Hamilton are on solid footing as well. Halifax is very close to securing their team, hopefully they can draw from the entire Maritimes and become successful there. Really it's just about poor BC and MTL teams as both those markets only support when team is winning. The big question mark is Toronto of course. Can the CFL survive without Toronto? I think so. They will not want to try that. As many have stated they draw real well on TV, it's just getting people to actually attend that they struggle with.
Normally I would NEVER recommend anything that the Bombers do, but in the past 5 years or so on the business side Toronto should certainly try to emulate. The Bombers have rebranded over the past 5-8 years not just as a sporting event and the game. They've made it so it's a party to come out to games. What I mean by this is they've embraced the NFL/NCAA model of making gameday a whole party. In their parking lots you can grill up food, drink, play loud music, party. More and more people are doing this. It's not just a football game, it's a party all night. If it's a Friday night game at 730, my group gets there at 430ish and we are by no means the first there. It's how football should be a whole day party. Embrace the fact that some will come just to drink at the bars in stadium, even the older folk that want no part of the party scene LOVE the antics of the Rum Hut section. It makes for a great gameday experience.