The reason why we would want Toronto to separate and form its own province is presumably because it gives us the liberty to direct all the taxes and revenues our (mega-)city generates towards our infrastructure, education and social services we need in order to build on our prosperity and success.
Our suburbs also generate a large percent of the province's income and also have a need and desire to invest in its local infrastructure. I wouldn't mind sharing Toronto's wealth with Hamilton, Mississauga or Waterloo because it is a good return on our investment, and conversely, having some of their revenue directed towards Toronto is a good thing too because a booming Toronto is a booming GTA. Further, the bigger we as a province are, the more political clout we have collectively to bargain at the federal level.
Ontario (and Canada) is not the rural country it was when the nation was confederated, we are now an exceedingly urban nation and our cities are the key to our nation's future. The current model is ineffective for investing in our cities and therefore in our future.
I know Mayor Nenshi of Calgary desires to get his city (and Edmonton's) greater access to available revenue tools, but I don't see that as a viable approach because the provincial government would never willingly give up its power. I think the most viable path for Toronto to attain those revenue tools would be through a referendum on accession.
(I am arguing one side, it is fun to think about but should a referendum on the issue actually come into being I think I would be much more conflicted on which way I vote.)