I don't know about SV, but foreign investment is pretty dam low in Victoria, BC, which could be used as a proxy for Vancouver. 97.8% were domestic buyers.[1]
It's not foreign buyers driving up the market in Vancouver, it's Canadians will to put themselves into serious debt in order to buy a house.
Did you read the article? They looked at the last names on the titles and if they were Mainland Chinese names they assumed they were foreigners, which is utterly ridiculous in the city of Vancouver where the population is almost 50% Asian, with most being multi-generational immigrants.
That's like doing the same study in Boston and claiming foreigner buyers from Ireland own 50% of Boston homes!
You get echo effects from places like Vancouver. Wealthy foreign buyers use high end real estate as a bank account increase the prices of top of the line housing significantly. Wealthier natives (Dentists?), now priced out of the highest end go down the scale and start purchasing lower end stuff with more money, increasing the price for everyone in a domino effect.
Government, not wanting the housing market to go down, create laws to allow subprime mortgage lending and buyers buy houses without real limits on price, and the middle class can now keep up with the price boom.
Well, it's been reported that foreign buyers are invested in a lot of the more expensive properties (> $3 million) in certain regions, but a lot of Canadians are STILL buying Vancouver properties. There's been a lot of concern over Canadians getting in over their heads with mortgages. It also doesn't help that Vancouver has crappy wages.
I'm not so sure about that, a lot of the conditions previously supporting real estate investment have given way. Oil's down, China is volatile, interest rates have risen, arguably you could say the trend could reverse due to people who previously bought as investments needing their money back.
That's assuming that they need their money back. The way I understand it is that there's a glut of money, and the rich are just piling it up and moving it around to where ever the best return seems to be.