I would imagine it wouldn’t be an overnight thing. My guess is they will have them for some time but will not be able to order any more. Say once they sell out, then it’s done...
Generally when the Canadian govt creates a new law, and places a date on that law, the change would become effective as per date, which in this case is Dec. 1st 2018. That has been my experience when working with some of these governing bodies, such as the CFIA.
To add to that, from the link on the new regulations that I previously posted: