Let's be realistic - how big is the market for anything over $100,000 Cdn, which may be the low end M X?
Once early adopters have snapped up the high end M Xs, there just won't be the demand - Gigafactory cost reductions or not.
Eventually, probably sooner than later, Musk will run out of other people's money.
Ask Smith(EV) trucks, how things went for them.