I agree with your alternatives to slow speculative activity-- but that is just the demand side. To help the supply side and pry those boomers (like myself-- but I am not interested in moving) out of their homes you need tax incentives. Most of my friends have paid off their mortgages and run their homes on 10-15,000 a year -- why would they move? Where in the City could they live cheaper?  Renting-- no, condos-- hell no (highest monthly fees in the country in Toronto).
UNLESS you are moving out of the City there is NO alternative-- that is poor planning and poor politics-- at all levels.

DUh-- there is this thing called a baby boom and guess what when they move (or not move) on any issue it creates a huge social/economic problem.  You want more supply without pushing up the prices any more-- give them tax incentives to get the hell out of their houses.