The effect of this is startling. In legal terms, where substantial ownership and effective control of an airline is not vested in a Member State or States, nationals of such a State or States, or both, or the airline is not licensed as a Community airline or does not have its principal place of business in the territory of the European Community,
any third country "may revoke, suspend or limit the operating authorisations or technical permissions or otherwise suspend or limit the operations" of the airline.
In as much as UK airlines will no longer be "Community airlines" (or even "Community air carriers"), they may be excluded from any or all EU-third country agreements. In fact, there probably is no "may" about it. UK overflight and landing rights in most third countries are automatically revoked.