[logfromblammo]

It wouldn't be any great upheaval. The component kingdoms of the UK would still be separately sovereign realms of the Commonwealth with the same monarch and royal succession. I imagine the process is now well established, as the Commonwealth has more than 50 countries in it, with 16 of them still constitutional monarchies.

.uk would probably remain just as grandfathered-in as it is right now, given that the official 2-letter country code is gb .