The GTA housing market is being influenced by some very unique circumstances which will likely prop the market up for another 10+ years, unless we suffer a complete economic collapse, which is certainly a possibility.
a few years back immigration laws changed in Canada so that very few immigrants without significant finances gain access. Asians, Indians and eastern europeans with very deep pockets are buying up every bit of single family dwelling stock available and often more than one home as they buy for children as well. Last year 112,000 new immigrants entered the GTA and only 12,000 new homes were built and a great many of these new immigrants are looking to buy.
As for existing single family dwellings, there is very, very little stock left and no room to build more in the inner GTA area. New home speculation is rampant in Milton and Oakville and some folks are making some nice $$$ off the current real estate anomoly caused by the immigration situation. Within Toronto itself, many economists are predicting single family home (not so much for condos) prices will rise 50% over the next 7-10 years.
There is, of course, a chance the market will dump, however, I would not count on it if I were looking for a home to buy for my family. If it were me, I would buy sooner rather than later.