As far as I understand the organization of upcoming European elections is under way, obviously with no British representation since the UK has triggered the process to remove itself from the union and it's too late to even imagine stalling that so even in the unlikely possibility that the UK would rescind Brexit (apparently the latest European Court of Justice ruling leaves room for it or stalling the deadline for exit despite the obvious impracticality) they would probably end up in some transitional status for the next few years regardless.
Basically quand le vin est tiré, il faut le boire or there's no coming back from this. I don't know a new Cabinet, whoever would end up in it, could alleviate it.
