JayADee:
Morgan says not to worry, you can owe this tax to the IRD and pay it when you either die or sell. So work hard, pay off your mortgage then owe a brand new one to the IRD if you can't afford to pay your house tax for whatever reason- sickness or age. You get to age while watching the house you 'own' slowly begin to belong to the government. Of course, Gareth will never experience this. Sure he'll have to pay more in taxes but as he's already said in a couple interviews, he can afford it! Yup, sounds very fair.
Part of my retirement plan is to run a reverse mortgage... I already expect to watch the house I 'own' slowly begin to belong to the bank. It's no big deal if the government also gets a slice, so long as it means that during (what remains of) my working life, I get to pay substantially less income tax.
So the (obvious?) response to GM's plan is to *not* build up equity in your home... run a mortgage for life. In fact, if the tax rate on equity is high enough and interest rate low enough (e.g. 5% tax vs 4% interest), it becomes worthwhile to borrow money against your house to avoid paying tax on your house. I'm sure that GM would then want to target cash in your bank account as well. Which in turn would lead to further avoidance strategies (trusts, overseas bank accounts, etc).