The important point is that lenders are better placed than borrowers to carry risk because they can diversify risks across many borrowers. Borrowers are willing to pay to reduce risk, either through a higher interest rate or through sharing their capital gains or losses with their lender.
In Canada’s case, with our strong standards for mortgage underwriting, the net result of such a reallocation of risk would likely be a safer financial system. Of course, there are many other possible variations on mortgage design, so many that it makes me wonder why so little has happened in our mortgage market in my lifetime.