The two most likely locations that I have heard for this project would be the Toronto Star lands at the foot of Yonge (this would definitely be a suitably iconic landmark for that unique location, and we do know that the land has been recently proposed for development), and between Elm and Gerrard (which has been mostly bought up by a single developer).
If it is built on the Toronto Star lands, the view from the Islands will be dramatically changed. This 100s+ megatower would rival the CN Tower in its domination of the downtown core. The view would be rather symmetrical, with a giant structure on each side of the CBD.
It it is built in the Elm/Gerrard site, it would serve as a link between the CBD and the Aura cluster -- although with all the new and proposed developments, pretty much all of Yonge south of Bloor would have a giant tower every few blocks.