The most ideal way would be to give 2 to china and some sort of 4 way fight for a final slot from the best remaining team from each region (perhaps a group stage where each team plays the other 3 teams once and the best team advances). But like you said, unlikely to happen.
Perhaps based off international results leading up to Champs is the most probable way to go (like winner of Tokyo) in deciding which region should get another slot.