There is zero indication that the British government would close off .io to non-Brits. You don't have to be a UK citizen or resident to get a .uk domain either.

There is zero indication that the British government would close off .io to non-Brits. You don't have to be a UK citizen or resident to get a .uk domain either. .eu requires citizenship or residency for registration, but most ccTLDs don't. The UK would not benefit in any way from cutting off .io registrations (or .sh for that matter).