The powers that be aren't quite sily enough to introduce a capital gains tax. And disallowing interest, although taked about, flies in the face of common sense and accounting practise anywhere. It amounts to a tax on turnover rather than on profit and that's unworkable. (Only Jim anderton thinks that sort of nonsense can work, for those who remember Jim - he was easily forgettable.)
So I'm picking the gummint will disallow depreciation as a deductible expense on residential property. That might not be a bad thing compared to any alternative. Land values usually increase so there's a built in compensation.