Whatever the change becomes (as I guessing man, it will be 18,000ft), the UK will also then have to resectorise most of its airspace too. I wouldn't expect it to come in sometime soon due to the huge complexities that will have to be solved as a result (ie, no changes can be made to the Gatwick stacks if they are to stay in their current positions. Willo will have to move about 30nm if a change IS needed).
18,000ft is due to the Upper Airspace in Europe starting at FL195. It is uncommon to lose two FL's due to pressure, so it means that the base levels on UARs that have no associated Airway will be available most of the time. Thats the reasoning I was told anyway.