what will happen to the Philippines If US-China war started.

After the war there won't be any more "US allies", ASEAN can be expanded to bring peace to northeast Asia. 

Chinese in the ASEAN, North America, and Europe will be put in concentration camps. 

@jason

The worst possible way you can think of. Before the US & China takes the the fight to either of their mainlands. The fight will happen in the Pacific islands and Southeast Asia first. The Philippines, Malaysia & Korea will be sandwiched because of the geographical location. 

@naval

There will be a global Han nationalism as a result.  

nukes will fly and the nuclear fallout will travel to Manila.