The reason Japan and South Korea will work with the US is because China is "eating their lunch," so to speak.
I agree with everything you wrote, the entire post.
Just want to say one comment on the above quoted.
As long as I have been alive, the trend is clear. China also into eating their lunch, of America, in terms of loosening South Korea and Japan away from the clutches of their patron.
China and South Korea only established diplomatic relations in 1992. Twenty years later or so, China already their biggest trading partner.
China and Japan relations still has friction, but it has improved from 10-20 years ago. Before China would still regularly bash Japan over issue like shrine visits and territorial disputes. That has not be the case the past few years.
Lastly, the most important consideration, how can anyone be sure of how much trust South Korea and Japan has in their backer?
How do we know that?
We do not.
Game on!