Nor is war as paramount as you make it out to be. Yunnan was under control of the NRA throughout the war.Industrialization is not the result of cost of labor... if it was then the Southern US would have industrialized first with its free labor, and the French would have industrialized before the British. And no, you have it reversed, dynasties were the abnormality in centralizing, most dynasties couldnt even control their own provinces without constant negotiating with local warlords to acknowledge the capital. By 1941 most of the major cities in that core Han area were already conquered such as Shanghai. Industrialization doesnt just "happen", the Japanese wont let have the Chinese have the time, money, outside technical support or resources to build weapons factories, they'd bomb them before being done. This isnt the Soviet Union building factories in the Urals.
And Tibet was independent already and the other peripherals you mention were Japanese occupied already; Taiwan for instance was already under Japanese control for almost two generations.
And as the Alexander, the Romans, the British, and Mongolians proved- population doesnt matter in war. Dont know why you think it does.
Second, population plays a factor in easier industrialization because of the specific situation I stated in my original post which you quoted. The situation involved a united China without the second sino Japanese war, in which China would have to pursue industrialization, meaning China would have the resources and technology it could purchase from the outside world. This also means that CKS would logically make use of the large population in China as a selling point to industrialists.
Finally, dynasties were not the abnormality. The negotiation with local warlords came in times of instability, such as the late Tang, late Qing and the late Han. Before their decline, dynastic rule was centralized and ruthless--centralization which frequently involved civil wars and purges to solidify. After their decline and growth in reigonal power, the nation would break up in a lull of warlords and reunify once more. China spends far more time united than shattered.