Ah excellent, this will surely alleviate the additional traffic in the area from IOL's move!
If anything, this will only help the downtown office crunch. Following link shows 528k sq.ft absorption last quarter, with 1.65 million sq ft. year to date. I think the core will be just fine, there are a ton of mid/large companies just itching to expand downtown, and I wouldn't be surprised if Brookfield's already got a new lease on IOL's Fifth Ave Place offices for after they leave.
http://www.collierscanada.com/~/medi...Q3%202012.ashx