New York Yankees, New York Mets.
I would say NYI and NYR, but in Canada, the baseball comparison is probably a better one.
From a sports perspective, you're spot on with the Yankees/Mets comparison. However, from a monetary standpoint...well, call me when Southern Ontario approaches
New York metro's population. There's more than enough money to go around in New York to support two teams (even three) in every major sport and make them amongst the richest in their respective leagues.
Toronto by itself has the Leafs (certainly amongst, if not the richest NHL franchise), the Raptors (top 1/3 of NBA franchises) and the Blue Jays (amongst the poorest MLB franchises). Southern Ontario supports those franchises admirably, but it's nowhere near the support given by the New York area.
A better baseball example is the most appropriate one - the Expos moving to the Washington D.C. area. The team went from a metro area with about 3.8 million people to one with around 9 million people that already supported a successful franchise (the Baltimore Orioles). MLB argued there would be enough support to justify the move once the new stadium was built and that there was a built-in fanbase screaming for a franchise. Sure enough, the Nationals are far more profitable than the Expos were and there are certainly Washington Nationals fans out there.
That said, the team is struggling to win games, they're having a hard time filling seats in that new stadium and the franchise suffered a
12% decline in value since last year. In other words, once the honeymoon ended, reality set in. In order to have a successful franchise, it needs to field a winning team, pure and simple.
I don't care what sport you want to talk about, winning teams make more money than losing ones and that's the biggest problem in Phoenix right now. Teams lose games, they lose fans, they lose money. It wouldn't be that much different in Southern Ontario, except that the honeymoon period may last longer.