We're missing out on all the complaints about spandrel, I guess.
None of Mississauga's neighbourhoods are precious enough to worry about gentrification. Maybe a hot take, but I think gentrification is a fact of life and people complain about it way too much. The only way to avoid gentrification is for a city to die. I think they should be allowed to evolve, as they always have done.
I think your observation is correct. Historically as one neighbourhood gentrifies, another (depressed) neighbourhood was often the benefactor of the displaced population and businesses of the gentrified neighbourhood, and so the cycle went.
But with our modern zoning codes, cities are not so organic anymore, and the displaced population and businesses don't necessarily have somewhere to go. In our region's context, they have typically been forced to locate in suburban neighbourhoods with inferior access to public services, more auto-dependence, and commercially hostile built forms (tower-in-the-park style, little opportunity for small businesses to locate).
Mississauga may seem like a clean slate, especially around Square One, but I am curious how areas like Cooksville develop especially once Hurontario LRT is completed.