I don't know the timeline but new buildings are going to be added to the SkyDome side of the CN Tower plaza, perhaps storefronts or restaurants. This is all part of the Aquarium project where the CN Tower wanted to reviltalize the base, monetizing its property and making it more of a daily use area used regularly by people -- not just visitors to the CN Tower.
I imagine that much time won't go by after the opening of the Aquarium for the next stages to follow.