Australia and New Zealand are an example but of course these are subject to the user friendly ICAO agreements.
It was mentioned earlier that perhaps the UK airlines will relocate to the EU with the jobs. Remember that in accordance with the ICAO world wide rules each state may grant preference for routes to its considered national airline: BA at Heathrow, KLM at Schiphol and Air France at Charles de Gaulle etc. The number of slots to destinations outside of the EU are where the major business is. If BA was to deregister from the UK they could lose their dominance at Heathrow and their routes. Since EASA came into being are there very many non british EASA pilots in BA or with our other UK airlines? It will be interesting to have data on this.