If they tried it would be what would happen if Vietnam had a long range air force shooting down their troop transports. Vietnam shot down 3000+ US fixed wings.I did not say anything like that. I said US military would try to degrade Chinese bases, missile launchers and possibly military production facility on the mainland in the event of a war. And depending on how much risk they are willing to take in the positioning of their carrier groups and how much risk Japan is willing to take in terms of the airports it would allow USAF to operate out of and a wide variety of other factors, China could potentially be dealing with a really large collection of missiles.
Keep in mind that China does have a geographical advantage, because it's operating out of its backyard, so everything in PLA would be at its disposal. It would also be able to repair bases and factories a lot quicker with all the available workers. But for the sake of the discussion, I can't pretend this is just a one sided exchange.
To hit targets in China that work on things with turnaround time fast enough to matter, like missiles and planes, US would need to strike places in the middle of China like Sichuan and Xi'an. That rules out all tactical aviation. They'll also need overflight rights from other countries or just ignore them for bombers. If they ignore, they'll be limited to cruise missile and their B-2 fleet since B-52s aren't stealthy enough to just ignore foreign airspace.
That means the only real pathway to attack Chinese MIC facilities is load up in Diego Garcia, overfly a foreign country like India or Myanmar stealthily, then overfly Tibet (high risk of crashing due to environmental issues), avoid all Chinese air defenses for thousands of km, strike a heavily defended target without immediate consequence for the front and make it back out. Not likely to happen.