To make any public transit project viable, we need density. A subway needs more density than a light rail line, a light rail line needs more than a streetcar, a streetcar needs more than a bus, and a bus needs more than a car.
There will be developers who would want to build projects that will not only support public transit, but add customers to the area's retailers.
The Spadina HRT subway was put down the middle of the Allen Road. Not very high density for a subway. To add more density to the Spadina, the city is looking at revitalizing
Lawrence-Allen, a couple of stations above Eglinton West. One part of the project is the decking of the Allen, similar to how they decked the Yonge HRT Subway between St. Clair and Rosedale stations.
We can expect to see other (maybe smaller) projects along Eglinton to increase the density to make the line viable. There are high-rises on Eglinton already, but I have seen notice boards at Eglinton and Martin Grove for projects for more buildings. I expect to see other notice boards coming up once they decide where the storage yards and station entrances are decided upon. So be on the lookout for those notice boards at the side of the road.