It's an interesting question, one I have been thinking about too. I'm not sure there is a place that combines a strong university town with easy access to (but separation from) Toronto and room for growth in quite the same way. Maybe St Catherines if they make Brock a huge priority? The former industrial sections are much like Kitchener was, just waiting for the right companies to need cheap space.

Ottawa is always going to be a government town first even though it has it's own tech scene, anything in the GTA gets swallowed by Toronto, Barrie and Brantford don't have universities, Windsor is too far from Toronto, but they might be able to piggyback on Detroit's revival if they play their cards right, London is stagnant and has been for decades, Kingston is on the wrong side of Toronto to really take advantage of Pearson, Guelph has already benefitted from Waterloo's explosion and the north is too harsh for many people.

I came to Waterloo for university about 15 years ago and never left. Despite real estate prices really jumping up, the investment in transit and transport through the region might mean south Kitchener and Cambridge are the next Waterloo.

KW is still a place where things make sense - a variety of housing with reasonable income multiples.