Housing is relatively affordable outside of Ontario and BC. Montreal, Calgary, Edmonton, Quebec City, Winnepeg, Halifax, Saskatoon, Regina, and St Johns are all major metro areas where homes are less than half the price of the GTA and Vancouver metro.
The obvious fix for Ontario and BC to make housing more affordable is to allow people to build more where people want to live by relaxing zoning requirements. In 80%+ of Vancouver and 60%+ of Toronto it's literally illegal to build anything besides detached single family homes. Little of the remaining land zoned for more dense development is suitable for development. There are some smaller changes like streamlining permitting, not exempting 100% of capital gains and incentivizing speculation, and a vacancy tax to discourage speculation that would help. The problem is any changes to make housing more affordable are politically unpopular, almost 70% of Canadians are homeowners and in the short term benefit from the status quo. Also younger people are ~20% less likely to vote.