Negative interest rates have a very odd effect on the financial math. Certain European countries are selling short-term debt at negative yields, which is somewhat odd. Specifically if you bought a bond from Germany with a 2-year term, you would receive a yield to maturity of -0.06%. If you just held your Euros under the bed, you would receive a yield of 0%.
This is somewhat of an interesting statement by the market in that holding Euro cash is more risky than holding German debt. The decoupling of sovereign debt and its underlying currency is quite steadfast in Europe, while it is highly unlikely you will see such an occurrence in Canada or the USA unless if investors have a good reason to believe that the Canadian dollar or the US dollar will be broken.
I will not talk at this point about Quebec separation and the impact to the Canadian dollar.