Not too much info at the moment, but an image has been floating around the internet, and apparently its appearance was preceded by rumours.
Although apparently a very preliminary design, the image shows a new glass walled building built on top of two or three historic buildings on Stephen Ave, as well the building on the corner, Hudson's Bay Store #3 (1891, Provincial Registered historic site) , shows 6 upper side windows in the image, indicating that 40% of the back end would be demolished (it currently has 10 windows).
It appears to also involve the Ashdown's Hardware building (1891) and possibly the Molson's bank (1911, Provincial historic site) and possibly beyond.