As long as the currency rotates people every few years, should not be a problem.

On the Macdonald issue....The USA doesn't change its' currency much for a few reasons, perhaps the most important being that it is the reserve currency of the world. (Perhaps MacDonald can be resurrected on the $50..not sure that outside of political longevity, and giving publicity to séances, what MacKenzie King accomplished.)

It is estimated that 75-80% of all us printed currency circulates outside of the USA itself.

Canada's currency does not fill the same role, as a domestic "scrip" it can more easily change and reflect what is "in" at the moment....

I still miss the two dollar bill, there was no immediate need to eliminate it.