Canada has never had a vaccination mandate for truckers and in all likelihood never will. It has a requirement that truckers crossing the border are vaccinated which reciprocates a requirement first put in place by the US.
They will not be forced to get vaccinated. No one has been forced to get vaccinated yet, and the provincial governments (it's not a federal jurisdiction) are unlikely to start doing so now.
The rest of the truckers will have to obtain a proof of vaccination BEFORE they are aloowed to drive their trucks again.