This is why putting LRT on Eglinton is such a bad idea. A developer wants to tear down the Celestica building at Eglinton/Don Mills and replace it with thousands of condo units.
http://www.blogto.com/city/2014/08/crosstown_lrt_spurs_massive_redevelopment_proposal/ It looks like Celestica will move to new buildings which occupy the eastern end of the site rather than moving to somewhere else in the GTA.
My guess is the Real Canadian Superstore will get redeveloped, as will the Ontario Science Centre parking lot, Church of Jesus Christ of Latter-Day Saints parking lot. There are probably also a few strip plazas and maybe some low rise office buildings that could be torn down to build more density. Expect tens of thousands of new residents at least once all these sites get redeveloped. This proposal alone says 2,897 units (claims they will be all 3 bedroom, seems rather unusual to me) which seems to suggest we will have about 10,000 people living in this development alone.
Has anyone at Metrolinx or TTC thought about what building massive condo developments will do to this line? My guess is that you will get several thousand new riders westbound during the peak hour of 8-9am on weekdays from a development of this size. Add in demand from the existing 20,000 or so residents of the Flemingdon Park area (who might walk or use bus 100), people transferring from bus routes 25 and 54, and people coming from further east and I have a suspicion that the LRT, if we don't change it to a subway now like we did with the Scarborough RT in the 1980s, and with no downtown relief line, will be overcrowded west of Don Mills, west in AM rush hour and east in PM rush hour. The inaccurate ridership projections that the Miller administration created are probably totally invalid if huge condo developments of this size get built, as I suspect that they assume that very little or no new development gets built along Eglinton and are totally invalid if that is not the case.
Don't count on the downtown relief line being built to deal with this problem because it is so expensive, so unlikely to get built anytime soon. Even if that does built, I'm not sure whether a new north south line will exactly mean that an east west line isn't still really busy, particularly in the long term. (The 401 is much busier than the Don Valley Parkway for instance).