On having a queen (who lives in another country) until someone comes up with an alternative that most can agree with, and then open up the Constitution to do it Canada is stuck with the status quo, simple as that.

Personally, I would offer Prince Harry the opportunity to come be King of Canada

Think about it:

1. The constitution is set up for monarchy.
2. He's never going to get the big job in the U.K.
3. If he marries Markle, she is American -which a perfect 'in-between' solution for Canada (the only thing lacking is a French or fn connection).
4. Markle is bi-racial - mega-bonus points for that one in today's climate
5. Their offspring would be proto-typical modern Canadians-foreign parents, etc..

A recent article ideas pointed out that on average people living in constitutional monarchy's are better off than people in republics (the nordics are all monarchies)
I think it would be the way to go....besides people are always going to have celebs, why not some real local ones?