The UK won the right to continue to clear euro denominated products when the ECJ ruled on March 4th in its favor.  Though appeals are possible for now this effectively invalidates the provisions of the ECB that euro clearers have to be in the eurozone.  The ruling is interesting – the ECJ ruled that the ECB was beyond it's competance which it said is limited to payment systems not clearing houses.  See this explanation of the verdict for more details.

You can see from the figures below and my post on the Clarus blog that nearly all the current and aspiring OTC euro clearing CCPs are based in London (or the US) today which would have made for a painful transition had the ECB provision been upheld.

OTC Cleared Euro Open Interest Outside / Inside the Eurozone