I'm actually surprised there isn't already a 2nd team in the Toronto area. They could pay a massive expansion fee AND would likely also chip in significantly with revenue sharing, so it would be a win for all the other teams. It's an underserved market. If TSN & Sportsnet were smart they'd make this happen, co-own the stadium but compete against each other with their own teams.
I think the only way a second team happens is a Rogers/Bell divorce as MLSE owners. Since that would be quite messy (i.e. each side would want the other to walk away, and each side would want the price of walking away to be so high it crushes the other), so using the territorial rights fee of an expansion teams as "phantom dollars" makes sense and serves everyone's best interest.
I.E. - The owner retaining MLSE has to buy out the other party for $7 gajillion, plus $750 million. The party walking away gets an expansion team in GTA for $750 million, but has to pay a rights fee to MLSE of $7 gajillion. The $7 gajillion wash out, so $750 goes from MLSE to the other 31 clubs.
Oh, and the NHL brokers it and says "we will sign off on this... if you both sign this document which specifically says your territory ends at the outer limits of Hamilton."
Everyone wins.
I think the Bears are to market dominant for a second NFL team to ever be considered for Chicago. It would be a Lakers/Clippers situation at best, probably even worse. I think Chicago would have a better shot with a 2nd NBA team, especially since the Bulls have been largely irrelevant for the last 2 decades. But I don't see any of the leagues adding to an already established market.
Here's the thing... OF COURSE any new team is starting as the redheaded stepchild to the established team. But that doesn't mean anything significant. The Clippers sold for $2 billion. The Mets and Angels are 6th and 8th on the most valuable list (White Sox 14th because of their stadium).
Same thing with a second Toronto team. A number of fans would say "I'm in on the new team because..
1. I wasn't around 100 years ago when the Leafs were formed but I can be in on this team since day one.
2. The Leafs haven't won a Cup in 60 years, might as well try my luck with the new team.
3. Leafs tickets are ridiculously hard to get.
And then you have kids. It's not about RIGHT NOW. It's about decades and centuries. Kids will make their team choice. The Arizona Diamondbacks wear non-traditional uniforms to appeal to kids because the adults grew up with someone else as their favorite team. They need to win 8-year olds, because anyone over 40 had a team before they existed.
No matter who it is, the second team is going to be a pretty solid franchise financially based on sheer volume of potential fans to draw from.