Looking at how the prospect of Brexit changed from "we'll bring you Empire 3000 and a pony" through "meh, it was all lies, but we won, nyah nyah" to "at least it won't be much worse than the Blitz...we hope," I believe that the conditions have changed enough. But whatever, let the British drive off a cliff if they so fervently desire their Splendid Isolation. Indeed, as you say, who am I to tell them "that's patently idiotic," even if I do think so.