Focusing on foreign buyers is a distractionary tactic. The primary cause of housing value spiking comes down to investors and speculators. Combat those, and the marketplace will return to sane valuations:
• Speculation tax of 50% of the assessed or sold home value (whichever is greater) of any home held for less than two years, decreasing on a daily basis to 0% over years 3 through 8. Exemptions can be had due to extenuating circumstances (military or police redeployment, divorce, death of co-holder of title, etc.). Because most pre-sales are snatched up by investors before ground has even been broken, only to be sold for two or three times its original value upon completion.
• Businesses (and by proxy, business owners that own multiple businesses) cannot own more than one rental residence per municipal district. This prevents speculators from buying up entire neighbourhoods just to jack up rents. There is a valid case for a business to own a residence (to host guests of the business), but anything more than the occasional guest can be put up in a hotel.
• Individual non-business landlords cannot derive more than 50% of their income from rental properties. Another method is to have taxes on rental income on a sliding scale depending on what proportion of their entire personal income rent is a part of, starting at normal rates up to 20% of income and rising to 100% taxation at the point where 100% of income is rental income.
The last one alone ought to protect people for whom landlording is NOT a full time job in of itself, such as people with mortgage helper suites or second homes that they upgraded from.
The point being, those with just one or three units are far less likely to be predatory than slumlords who own entire apartment blocks or institutional investors that own a significant block of rental units in a city.
And such a progressive taxation scheme ought to materially prevent rentals from being dominated by a handful of investors.