At least in the US, up until the rise of 'flipping' and AirBnB home values typically tracked with inflation. Personally owned real estate was a hedge against inflation and a tax shelter, not an 'investment'.

> It can be both affordable and an investment

By definition if something is affordable, it’s not a good place to store money with the goal of it increasing.

> All of the items above can have drastic unintended consequences.

Yes, absolutely. These are not fully fledged solutions, but a starting point. Some of them may need an asterisk or two. Of course, unintended consequences are perfectly fine if the final result is better than what we have today

> I can't add an ADU to my existing property which would add one more dwelling unit

Your wife or kid could own it. If you don’t have either of those, you don’t need two homes.

> Subdivision of property is discouraged

Subdivision and sell is perfectly encouraged.

> This might be the closest to doing something though it could substantially discourage non-citizen immigrants (legal or not)

I am a non citizen immigrant in Canada. I just had to bide my time until I became a PR then could buy a house. Perfect.

> This has been tried before and had well-documented issues, but might be doable if they can provide a "floor"

Again, it doesn’t have to be perfect, just better than what we have now.

> it could substantially discourage non-citizen immigrants (legal or not)

Make an exception for owner-occupiers?