Japan is still and independent country full of Japanese people, who held their own against Western militaries within decades of opening. That's a very different

Japan is still and independent country full of Japanese people, who held their own against Western militaries within decades of opening. That's a very different from the apocalyptic collapse followed by replacement of the New World. Of course, there's a huge difference between the two: Japan always had some contact with the Old World, and with Old World diseases in particular. America would probably have faced the same wave of disease, even if discovery had happened much later.