I think you're really far off on this point. In most ways, China is the only country in the world that's capable of fighting a long term intensive war. Most countries with advanced militaries have very small munitions stockpiles, and they will run out of munitions within weeks, if not days. For perspective, France ran out of precision weapons in just a couple of weeks when they intervened in Libya, and that's against a country that basically couldn't fight back! The US is in better shape, but even they don't have that much in weapons stockpiles, and these are unlikely to last more than a few months. At which point, there's just not enough production capability to make up for the shortfall.Current level is sustainable, but it is only a peacetime posture with a total force of less than 2 million. Once war starts, you need to pay for sudden surge in man power, munitions, logistics, and more importantly, payouts and healthcare to the wounded and the dead. You are talking about sudden surge in spending and resources. If the war drags out, not sure how long you could sustain such war economy. Image sustaining a 5-6 million strong PLA for a period of 5 years should a war drags out. And this occurs whilst China’s economy is completely cutoff from the world. And as soon as the war ends, you need provide the huge sums of payouts and healthcare benefits to the wounded and families of the dead. The country’s debt is going to skyrocket.
In comparison, while it's not publicized, we can safely infer that China does make a lot of advanced munitions and keeps large stockpiles. Moreover, it's way easier for China to scale up production on these weapons than for anyone else to do so. A long term conflict is all about who has the most industrial capability and electrial generation capacity, and guess who leads the world in both these metrics? And by a freaking lot?
The other big factors are about control of supply chains, and stockpiles of strategic materials, and the ability to produce intermediate goods. The US and most of the West doesn't believe in any of these so do you think any of them can sustain a long term war?