This is my impression of the situation for lots around Clyde-Queen:

(image hosted by me)
A-C are the "sisters" sites. D is the library site. E is a proposed park (not sure if there are concrete plans to construct it -- will it be built at the same time as the library?). The yellow site is Morris and Queen and the blue site is the IDEA building. Both are owned by Dal.
The sites of the City Centre Atlantic addition and the new TD building are also both in this shot (and the proposed new Chickenburger, I think above site "A" on Queen Street). I guess we could theoretically have 5 things under construction in this small area -- the first Clyde Street site, the library, IDEA building, TD, and CCA.