Speaking of the Sheppard corridor: the city cannot afford to extend Sheppard subway in the near future, as is has committed serious money to Danforth - Scarborough subway.
The city council narrowly backed Scarborough subway (24 to 20), but it will not back a second subway to STC. If such proposal is presented for a vote, councilors from other parts of the city will demand subways to their wards instead.
That leaves only a few options: Sheppard LRT as planned; modified Sheppard LRT or BRT within $1.1 billion allocated for this corridor; or nothing at all.
Maybe, the solution is to conduct a poll in the area, east of Hwy 404 and bounded by Finch and Ellesmere. It does not have to be a formal plebiscite; a large phone-based poll should be sufficient. The participants should be clearly informed that a) LRT is not as fast as subway but is faster and more reliable than bus; b) all through traffic lanes will be preserved, only the central left-turn lanes will be lost; c) if they reject LRT, the city will not start planning the subway for at least 15 years, and will not build it for at least 25 years.
If the majority turns out against LRT, then the project should be cancelled and the funding transferred to other projects, such as DRL, SmartTrack, extending Eglinton to the airport, extending Finch LRT to Yonge, or building Waterfront East LRT.
Although, I doubt that merchants concerned about the loss of left turns represent a sizeable portion of the local population. The count of businesses potentially affected should not be more than say 100. With family members and employees, that translates to perhaps 1,000 voters. The total population of this area is probably no less than 100,000.