Well...
I'm expecting a goodly number of my clients will arrange to be tax-resident in another country; one that has a tax-treaty with the UK and thus overrides the 90 day rule. If you have a "permanent" residence in only one of the two countries, you are resident only in that other country, even if you exceed the 90 day rule. Then Bob's your uncle; the UK loses some trillion £ in tax all for the want to collecting an extra £250 million.
The word in this week's Economist is that faced with trillions of pounds of lost other taxes (the annual amount of VAT, income tax, and stamp duty paid by nondoms is in the billions), it would be fiscal suicide for the government to continue with the proposal in its current state. The Economist also predicted he would likely lose face if not his office over this fiasco.