True, but article 50 has always been part of the Treaty on European Union (TEU). So EU citizen moving to the UK must have known on the day they decided to migr

True, but article 50 has always been part of the Treaty on European Union (TEU). So EU citizen moving to the UK must have known on the day they decided to migrate that their entitlement to live in the UK was always subject to this caveat. It may suck, but it was never an right that could never be revoked.