The people making money right now from those additional people coming into the GTA - are the developers! They're the ones who buy the land and then put up that building and then sell it in overpriced little chunks. The ones who buy those overpriced little chunks are rolling the dice.
Historically, real estate has been a good investment, most of the time. But the market can only withstand SO much. Housing in the GTA is on the limit of affordability for most normal people and I think it's unreasonable to expect that it will go to a significantly greater percentage of people's income (where is the money going to come from?). On top of that, interest rates are more likely to go up than down in the long term and they sure have a lot more room to go up, than they do to go down. If the interest rates go up, it drives affordability in the wrong direction and that tends to drive prices down. On the other hand, if the economy continues to stumble, which postpones the increase in interest rates, that results in average income not increasing, which means there is not room for the cost of housing to go up.
My view at this point is that it's wise to buy a place to live in, but not to rely on it as an income source.