I presume Air Canada would only look to route to one of their hubs, but they have service to three of them and Calgary would seem a stretch, considering WestJet already serve it and it's not the best location for connections.
WestJet themselves could perhaps see potential in Edmonton or Winnipeg, but as an airline that has 10% of its fleet as 737Maxs, I'd be surprised to see any immediate expansion.
Then of the three bis US carriers, Delta to Detroit, United to Houston or American to Phoenix could all make some kind of sense.