If you are going to bring another franchise to Toronto, it better be in the 905 or Hamilton (which is it's own separate city). The franchise would need it's own separate identity from Toronto. But even then, I don't see a NHL franchise in Markham, Mississauga or Brampton doing well. Look at the Mississauga/Brampton experiment in the OHL... I live in Mississauga, about a 10 minutes drive away from the Hersey Centre and I have absolutely no desire to go see the Mississauga Steelheads. Mississauga doesn't have that kind of culture.
Long Island is a very different beast from New York. So putting a franchise in Long Island made sense. The team is in Brooklyn now. Which is a shame. Brooklyn and Nassau-Suffolk county are world's apart culturally. Just like Manhattan (NY Rangers) is different from Nassau-Suffolk and even Brooklyn. Just like how Manhattan is different from Harlem or the Bronx. People in Nassau-Suffolk can still commute to Barclay's in Brooklyn to see the Islanders. But it's just not the same anymore. It's not their team anymore. Long Island pride is a thing. Mississauga pride? Not so much. lol. Hazel McCallion and the city councillors left us debt-free for a very long time. And Mississauga has more jobs than it has workers living in Mississauga. They have a strong local economy for a suburb. My Mississauga pride ends there. lol.