No second Sino Japanese war

What would have happened with the treaty ports and foreign concessions (and to a lesser extent exteritolarity) without a second Japanese war. In OTL the war brought great suffering and destruction but ended with the allied powers agreeing to return theirs to China . the axis lost them as a result of the war , and Japan agree to return all territory gained.
Could China have annulled eventually
anyway?
How did Japan renegotiate theirs in OTL?
 
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