And if today's market is the bubble many think, then selling the house after it bursts may not net enough to pay off the loan.
I'm no expert, but to the best of my knowledge:
The lender (CHIP) cannot demand more than the "fair market value" sale price of the home as determined at the time of the sale, even if it is less than the outstanding reverse mortgage balance at the time of sale. This is a major difference as compared to reverse mortgages in the USA. (US reverse mortgages are usually far more risky and costly in general.)
CHIP will only loan a maximum of 55% of a conservative appraisal of the property's value, depending on the location of the home, age of the owners, etc., etc. Obviously the older the owners, the closer to the maximum the loan can be. The average loan is 35% of the property's appraised value. It is highly unusual for the value of a home at the time of the ultimate sale, especially in the GTA, to be less than the outstanding loan balance. So far selling prices in the GTA have usually been considerably higher than the amount required to pay off the reverse mortgage, and the owners or their heirs get to keep the difference.
That said, the interest rates involved are quite high, and if the owners can qualify through sufficiently high actual annual income or very high equity for a regular first or second mortgage or Line Of Credit, those possibilities should definitely be investigated, as well as considering selling the home to generate cash for ongoing living expenses, and downsizing to a smaller home or even a rental.