It's possible, but it would take a major meltdown (worse than the US). Banks don't want this. If banks want anything, it's a controlled decrease in prices... or a "soft landing" like we keep hearing about. The banks know that legalities mean nothing if a country is bankrupt or heading there. Remember, this is still a democracy we live in. Mob mentality and public outrage will defeat any court order or government plan. If banks are posting record profits and collecting 100% insurance claims on the backs of canadian tax payers (who are all watching their house prices plunge and losing their jobs), then that's how a revolution starts. Just look at Greece. As soon as things got bad, then pensions got cut along with numerous other things.
If a Government can cut pensions (which were promised) to citizens, then why can't they cut CMHC insurance fees which were also promised? Citizens paid into pensions their whole life the same way homeowners paid into CMHC insurance. If things do get bad, then the government can do anything they want. Keeping a country solvent comes before anything else, and so if things were to get bad enough banks would be the first ones to take a cut. But if it came to this, the banks probably would step up to the plate anyways and take on a ton of near worthless bonds, etc.