I would be very surprised to see either the Sears store torn down, or for the lower floors to go non-retail. I wouldn't be surprised though to see some massive reconfigurations of the space to accommodate more stores while Sears shrinks. The very successful galleria could be extended further north for example, or the southeast chunk of Sears could be amputated, leaving Sears as an L shape, and providing space for another store (like Simons) with access to both the mall and Yonge Street. (Not that Sears is going to be thrilling giving over space to more direct competition.)
I would be surprised if Sears would let 1 below go entirely, and moved itself up on to the ground and higher floors only. Surely 1 below (or whatever it's called) has high traffic, and good sales, due to the number of people on their way to or from the subway and galleria.
The higher shuttered floors need to be rethought. Who wants to ride escalator after escalator after escalator to get to them? No-one, that's why they're gone. Reconfiguring them for Ryerson would make a lot of sense once access to them was improved, e.g. a skybridge from the new building, plus a better elevator lobby at ground level, etc.
I have no idea what Cadillac Fairview's lease allows, or when it's up for renewal, but some creative thinking needs to be applied to the building.
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