NamelesStatistic
Banned
Give it a few decades to stew and create something interesting first, but eventually toppled, sure.
Remember that if this is a Soviet backed North Korean-esque communist dictatorship it would be quite easy for the US to invoke the Monroe doctrine (Soviet interference in a North American state) to justify a military invasion as soon ASAP. They wouldn't really have to wait for the new Canadian dictatorship to cause an incident to justify military intervention (ie. with Japan in WW2).
NOTE: In OTL the Monroe doctrine was actually applied to Canada in 1938 by FDR, who stated that any "foreign power" that tried to "dominate" Canada would face a declaration of war from the United States. (Queens University address, page 4). This statement was obviously aimed at the Germans, but it does show that the US was unwilling to risk any threat to the safety of its northern border.