As long as China controls South China Sea, this kind of exercises, alliances, or even asian NATO are useless. The diamond alliance has a major defect, China controls South China Sea. All trade and military collaboration can be monitored or controlled by Chinese Forces in South China Sea.
Actually the more exercise, the bigger military bases in South China Sea. Before any pivotal to asia, China is reluctant to do reclamation in South China sea; now solid foundation to do this.
With DF-21D and DF-26, united states' control within first island chain is loosing. With China + USA GDP 40% of world for last 70 years and incoming 70 years, sooner or later USA will change the strategy. Someone will be sacrificed.
China and USA collaborated on WWII and cold war. There may be a third major collaboration. When that time comes, it will be nightmare time for Japan and Phillipines.