You're over thinking it.

1. Eliminate the investor and land lord element from real estate and you reduce a significant reason as to why housing is so expensive. Do it with taxes, codes, whatever. You can own two houses and any more than that the taxes go way up. Landlords don't build houses, developers who sell their new builds do.

2. Eliminate foreign ownership of American real estate and limit it to American citizens and legal immigrants. -> see Thailand

3. Unpopular but true: eliminate the influx of illegal immigrants and remove the ones already present. More people + limited stock = high prices