At that point it won't really be Japan anymore, and where will you go?
Local population can be relegated to a minority and what makes Japan alluring today will still exist just fine. There's nothing about a particular people, with a particular culture, and a particular approach, having built a country of a particular outlook.
Besides, we can improve the norms we don't like. And of course, we totally deserve to live there, after all we've watched all these anime and ate so much sushi...