I think instead of underrating China's ability to fight a regional war, we should stop overestimating the USA ability to fight a far away war. War of such magnitude don't get done in days or weeks, and the countermeasure that China could deliver is something the USA never had to face before so lets break it down into a hot war scenario between both countries. To even contemplate starting such a war the USA must have full support from the countries it wish to launch it's war in, the obvious choices are Japan and Korea, and Singapore (possibly India), the other are Guam and Australia which are both abit out of reach. A hypothetical scenario in which both Korea and japan agree to help the USA with rearmament of munitions used, repair and servicing of arms, and reconstruction of damaged infrastructure, that will still leave the Americans short when it comes to negating the impact of the Chinese manpower and proximity to rearm and produce host and host of missiles that could swarm these bases. Compared to American military asset in the pacific, China's asset are also far greater both in missiles and Naval, air facilities. The USA will be unable to overcome this logistic chocking point given the current reality. For example they may have 11 aircraft carriers roaming the seas, but there is no way for them to base all 11 in the pacific at a given time. Only a few type of ports could host, service and rearm these carriers, and political and economic reasons as well point to this as futility. Second these aircraft carriers if proven to be vulnerable to submarine, air and balistic missile attacks, something again the USA never have to faced in the countries they choose to invade, it would be a moot point because surely in times of war they would be the first target along with the American bases in the first countermeasure phase. Bearing in mind that these carriers must be at the very least 500 Km away from Chinese coastline to be even effective, with the latest F-35. In these type of wars stealth and range matters and it matters a whole lot, missiles are far cheaper and have more range, and far easier to produce in numbers, till America is able to produce a fool proof missile defense shield that point is moot. China again at this point is able to with homefield advantage field far more and far quicker of anything the Americans can throw on them, in the end if it is a war of attrition, you can guess who is the victor. America will run out of resources within a year, because they are not able to logistically support their bases 10000 miles away. For America it is about building up coalition and hope with fingers crossed other countries do their dirty work for them so they don't have to. To summarize things up will America win a regional all out war against China by themselves in the pacific? The answer, an impossibility. Will it be a stalemate? Possibly for awhile till America runs out of airbases, munitions ports to fight with, then maybe they could lob a few nukes from submarines, and expect a reciprocal response, but that is about it.
The Americans have been training for decades for this particular scenario vis-a-vis the Soviets. And keep in mind that the Soviets were lot more dangerous then, than the Chinese are now.
BTW, the US did win a war in the Pacific, against an evenly matched Japanese empire. And it did it on all its own, with another war in the European theatre.
Is China willing to bombard US bases in sovereign countries? This would mean a declaration of war all over South Asia. Does this mean that China is willing to tangle with the Koreans and the Japanese, while being in simultaneous war with the Taiwanese and the Americans?
China does this and the logistics train problem solves itself.
Also, the manpower argument is a fallacy in my opinion. A pilot, a submariner or even an infantry officer takes years to mature and become effective, you cannot just hope to throw in new recruits in battle and expect victory.
Do you really think that NATO will not lend a hand if it becomes a war of attrition? Most of NATO is supported by the Americans.
All Carrier groups are protected by a screen of the most potent warships in human history, not to mention an air arm of atleast 90+ aircraft. All this plus god knows how many land based aircraft. They aren't as helpless as you may think.
You can lob ten thousand missiles at Taiwan, but until the first Chinese infantry boot hits the Taiwanese beaches, Taiwan will still be free. I am assuming that this would be the most logical flash point.
Also, a lot of strategic targets [dams, power-plants etc] will be hit by stealth platforms operating out of the continental US. No need for overseas bases.
Finally, the US has one of the most abundant pile of natural resources in the world. Canada, Mexico and other South American countries will pickup all the slack for resource supply and industrial capacity. Also, there will be trans Atlantic trade, China can never disrupt that. And US has been trading with the Europeans lot longer than the Chinese. It will hurt for a while sure, but these places were US trade partners before the Chinese took their place.
China on the other hand, is an export based economy and without its biggest customer, it would collapse. Losing the US, Japan, Korea, India and Europe all at once will play merry hell with the economy.