You can still get a UK ATPL if you had an EASA ATPL before the split and you take the time to do a UK initial medical. No exams needed. (Until the end of 27, after which you can’t moan about it, you had fully 7 years)
Also, if you think that the right to live and work in either region is wholly relevant you’re mistaken, plenty of people are able to commute and not fall foul of the 90 day rule. The airlines will find a way if they’re not able to fill their seats.
Having both licences for many of us will be a huge boon in the years to come and, purely selfishly - having gone through the expense and effort to get my licensing in order - I have zero interest in cross border licensing arrangements.
This policy is good for UK and EASA pilots, particularly if you took advantage of the ample time to get your licence on both sides.