Investor immigrant programs can have benefits outside of the housing market.  Basing income levels on what "would be required" is a bit of a hazy accounting concept.

If you really want to design a policy to make housing affordable to local workers, put restrictions on the 'free' housing market.  I know that goes against the worldview of those that trade pork belly futures and equity call options for a living- but we're talking about the market for homes. What makes homes such a great investment for domestic and foreign buyers is - it's a home.  It's not subject to product risk -becoming obsolete or going out of style.  It's a damn home.  

So foreign buyers - you're taxed. Or better yet, you can't buy our homes unless you work or live here.  Domestic buyers - sure there is a benefit to investors improving and re-selling.  And to landlords providing rentals. But there is a limit to how much you can own too.  You can buy as many widgets as you want. But not homes. We live in them.