This design is too iconic. Every major city and every architect firm in the world has a knockoff of this stacked toy blocks, design motif ready to go. The trouble is, once you've seen this trick it gets old fast. Also, any city can have only one of them or else it looks like the next one is a copy and everyone comments as such. How many Frank Gehry Bilbao Museums can one city have?
So, I don't doubt Toronto will get one of these soon, but it better be a good one, because it's the only one we will (or should) get.