Perhaps then it's a generational thing -- some people are old enough to remember when say Scarborough was clearly sparsely populated suburb and Markham was still undeveloped farmland, whereas the younger generation less and less so; someone, now a teenager, say born in 2000 will have only remembered a world where Toronto always ended at Steeles and Mississauga was always a neighbouring city with a skyline. People's perceptions of their hometown after all are shaped by their own experience in terms of what they saw at the particular time and place they were growing up in it.
Perhaps, over time, as a new generation comes of age, people will grow up thinking it's normal to just call Etobicoke or Scarborough the "city" and somewhere like Vaughan "the suburbs".
Unless of course, residents of Toronto's old boroughs continue to identify strongly with them (as some certainly do!) so that their identities remain long-lasting, such as people still seeing Scarborough as their "hometown" that's distinctive in some way from old Toronto. I mean, people in Brookyln or the Bronx still speak of Manhattan as the "city" despite amalgamation having happened a century before Toronto's boroughs did! Who knows if Toronto's own boroughs and their own residents' view of them will have such staying power?
