They no longer have the ability or will. They do need to be VERY concerned that they do not allow China to establish regional hegemony. China has both the ability AND the will. In fact, they have a plan and are executing it. Japan, South Korea and Taiwan have a combined GDP of only about half that of China, and unless they are ready to accept their new Chinese masters, they better get together with a coherent plan themselves.
Your estimates of China’s GDP relative to Japan, South Korea, and Taiwan are not current or correct. The Chinese economy has shrunk rapidly since Trump implemented tariffs. Japan’s economy has grown significantly since the new US-Japan Bilateral Trade Agreement. The Japanese were smart enough to work with President Trump very early. Their competitors, like Germany, France, the UK, and particularly China, all dragged their feet and have suffered tremendously.
You have to realize that the Chinese are inveterate liars. Any statistic they claim is undoubtedly false and likely significantly overinflated to overstate their successes and underplay their problems.