Unlikely.

First, Manchuria IS China. Before the Japanese invaded it was run by a Chinese warlord who went on to literally kidnap Chiang-Kai Shek in order to get him to agree to end his encirclement campaigns of the communists and instead focus on the Japanese. Chiang himself probably also thought war was inevitable with Japan. So in that sense the Chinese were never going to allow the continued occupation of their land forever.

A lack of war would likely allow Chiang's nationalists to consolidate itself by finishing its encirclement campaigns on the Communists. The rest of the warlords would follow in due time I'd imagine. While its unlikely China would launch some sort of offensive war in the WW2 timescale, it is unlikely they would wait forever when much of their ideology and history in those recent decades was based on undoing the "century of humiliation" - which would mean the foreign concessions would gave to go, including Japan.

But beyond that, if WW2 still goes the same way - Japan is still loosing. The might of the UK, then combined with the US and then the USSR would still be more than enough to put Japan down even if it weren't tied up in Chinese affairs. The end result would probably end with much, if not all, of Manchuria being returned to China as we saw in real life. And the only reason some of it might not be is because we can't ever be too sure what the allied powers would've taken had they been given a freer hand in Manchuria at the end if the war. Either way the clock was ticking for Japan.

It is also worth mentioning that much of China's more modern and trade industries were based in Shanghai. It was a very,very important economic hub for Chiang's nationalists. One that he threw his best troops at in order to try to preserve.

But also it was a fight within sight of the world. Shanghai was a modern city by Chinese terms and it was one with an International Settlement that could actually show themselves off to the world.