China's Selective Export Tax Rebate

China has announced that it will cut back on rebates of its export tax (which is designed to replicate its value added tax).  Rebates of indirect taxes are OK under WTO law (see item (g) of the Illustrative List in Annex 1 of the SCM Agreement), but it would seem that the move to selective application would raise the issue of whether the continuing rebates are export subsidies.  Where "government revenue that is otherwise due is foregone" this constitutes a financial contribution under the SCM Agreement.  But the history of the Chinese measure does not quite fit, as the change is not to forego, but to stop foregoing some revenue.