I admired your optimism. I really do, but you tend to simplify things about politic in East/South East Asia in a geopolitical level...
Remember the "trust" issue I raised on another post with you? The problem is, while you are thinking it would be the west all along to try to divide and conquer Asia, but the unfortunate truth is, I am afraid Asia have been doing this all the time before even the west have known there is a place called "Asia" exist.
If you look at China's 5000 years history, you will see a pattern of all sort of wars raising all around South/East Asia all the time every 100 or so years. Like this Gif Represent
View attachment 290004
The problem is, this is only China and its conquest during the last 3000 years, there are many other in South Asia, Middle East, and West Asia. What the west does? The west simply capitalize on their warring state and basically strike when there were already chaos everywhere. And nothing beats making money on a chaos world.
It cannot be a "trusted" states exist in all Asiatic country, there were always going to be a war or disagreement somewhere happening within Asia with or without the west meddling. The problem is, while blaming the west indeed shifting blame somewhere else, it does not solve the "trust" issue between each Asian country, and what you said, a Greater Asian Union can only actually happened by either each country totally trust the others of the said union, or one country dominate them all. And while I have already explained why the first one cannot be done, the second one would be the only choice for Asia to unite. However, who would be the dominate force of a united Asia? Long story really short, it's gonna be China.
Much like how US become the sole leader of North and Central America. If there is going to be a united Asia, then China have to dominate the whole Asiatic region, but unlike the US, which only bother 2 countries, China was surrounded by heck a lot of small country and each one of them China have to dominate either by choice or by force to be able to rightfully claim the dominance and hence lead the Asian Union. But for that to happen, once again, would you think other Asian Country would trust the "Chinese Peaceful Rise" with guns pointing at them?
The problem is, what China is doing today is basically blaming the west for meddling the Asiatic Affair which the west does not belong ad basically using this to expand their gain and dominance, for the sake of "getting rid of the west" but when you come to think of it, wasn't this is the exact the same slogan the Japanese used during WW2 to grab land in Asia? For the sake of getting rid of "Western Colony"?
Now, would the rest of the Asia actually see this as any sort of good to them for the "Peaceful Rise" of China? As I said, it always take two to tango, and whatever the west or US is doing, it cannot succeed if there does not exist another party that willing to play the "Bad Guys" on the US Script, and for that, China have fall into it quite nicely.