The Canadian manufacturing sector is already hit hard by the rise of loony, competition from China and US recession, if the US opt out NAFTA, it will pretty much send this sector to the death bed. The manufacturing sector is critical in Ontario and Quebec, I can't imagine other sectors (including IT) will do too well if we continue to suffer huge job losses in manufacturing sector. And what if Canada retaliate by restricting export of oil, gas and other energy products to the US? Those sectors will be affected too.