There are 2 main ways ahead:
Either to develop an IMC rating (or whatever you wish to call it) which everyone else in the EC can obtain.
or to establish a process by which the IMC rating may continue to be issued and used purely in the UK post-EASA.
The whole 'my Rating is better than yours' nonsense needs to stop. Whether people want an IMC rating or an IR should be up to them; personally I wouldn't ever want to fly a spamcan on European airways, but others might.
It came as an obvious surprise to M. Sivel to learn that, whereas an FAA PPL IR holder is never retested, an IMC rating holder has a mandatory re-test with an Examiner every 2 years.
Presumably the PPL/IR Europe group consulted those of its members who only hold IMC ratings to elicit their opinions before presenting its opinion through the EAS delegate on FCL.008?