Canada won't face a shortage, since it can always just prematurely expire the patents on any given drug and allow its domestic manufacture. That would really change the pharma game.
A lot of people on FR think the U.S. consumer is subsidizing the lower price of drugs in Canada by paying higher prices here. Actually, the prices set in Canada still provide a profit for the drugs sold. The pharmaceutical companies are not at a loss because of proice controls. They are not forced to sell below or at cost.