Economists believe that prices of goods represent that anchor. In the long run, the Canadian dollar will only depreciate against the U.S. dollar if Canada's inflation rate is persistently higher than the U.S.'s. A bubble occurs when expectations do not have an anchor. Expectations are self-fulfilling. If the depreciation of the Canadian dollar were a bubble, it could explain why producers have not abandoned Canadian markets.
Bubbles eventually burst, and when they do there can be huge swings in asset prices.
Those U.S. producers that have made inroads into the Canadian market might not be willing to abandon the market under current circumstances. They may have undertaken substantial research and investment to be able to provide their goods to Canadian markets. With the current weakness of the Canadian dollar, their profit margins are squeezed. But they will not abandon the market if they believe the foreign exchange market has a bubble that might burst dramatically. It will be better to ride out the current situation and wait until Canadian sales are again profitable than to abandon the market altogether.