They can if they want to..... They just have to deem EASA regulations as being acceptable
And why would they not do that? After a decade or more of saying that these regulations are OK you wouldn’t overnight turn around and say otherwise... or would you?
It’s my belief that as with U.K.-to JAA and JAA to EASA there will be a transition period where both U.K. and EASA would be acceptable. You can’t simply switch it off.