Not really, or at least not entirely. Here’s a link that goes into some detail. It basically comes down to: referendums are fine and legal; secession has to be agreed to by the area leaving and the country as a whole; and subgroups of the region seceeding likely have the option to not seceed depending on their legal status. The Supreme Court has already determined that unilateral declarations of independence are unconstitutional in Canada, and I suspect the notwithstanding clause won’t apply, either.