Earlier quoted context omitted.
If that happens house prices will go apeshit.
What's the argument for negative interest rates having any impact on house prices? I would think it would be mostly linear compared to 2%, 1%, 0%, -1%, etc... For example - if I have a 20 year mortgage on a $240,000 house @ 0%, I have to pay $1,000/month. If the interest rate is -1% then I have to pay ~$900/month. I don't know if that extra $100/month really moves the market on home prices that much.
With negative rates the payments compound. If the interest rate is $900/month, you're paying off $1000/month in principal each month, and making $100/month in profit that is applied to the home equity. You can then go use that equity to take out another loan on the property, make $100/month in profit, repeat. Or go buy a different property with a different lender, if the bank starts getting suspicious. If you can't afford the increased payments...well, that's what a loan is for, particularly one that you're making a profit off. ;-)