You have some good posts, Mr. Guest - I have come across a number of them. But here I think you are off.
From a very historical point of view, the exact opposite conclusion is reached. The best and most one can expect of Sino-Japanese relationship into the future is one of "cordiality".
So there is this "talk" of "East Asian Co-prosperity Sphere" 2.0. You should know the context of this talk, which has virtually nothing to do with China, but everything to do with Japan's own complex psychology.
It's also a way to get Uncle to pay attention to the Geisha, who is not feeling what she wants to feel ...
We all know 1.0 was a bloodbath, and 2.0 is, well, propaganda.
End of story.
China will stick to Pakistan, barring "X-factors" that are in the hands of the Almighty. And if India stands down with Pakistan, then China will turn to India, too.
That's of course, assuming all three countries survive their respective internal instabilities well into the future ... China's internal cohesion is not something to be taken for granted.