If you look at how many submarines the US has and can build, it doesn't look favourable.
Technological trends also are going against large nuclear submarines, with big data and large numbers of automated detection platforms.
And the land-attack capability of US submarines is limited to slow, non-stealthy Tomahawk class missiles.
3 years ago, I would have agreed with point 3
However, I think the balance has shifted significantly, so that China does have the ability to keep US submarines at bay and also keep the US from using local bases in the Western Pacific. And when we're talking about preventing the US from using local bases in the Western Pacific, we're essentially talking about Chinese capability to impose an air-sea blockade on Japan and the Philippines.
In the event of a blockade, Taiwan, Japan and the Philippines are small densely populated island(s) with no natural resources and dependent on imports of food and fuel. They would collapse far faster than China which is geographically the same size as the Continental US and can therefore be largely self sufficient.
So I reckon China would largely be able to protect its industry and churn out significantly more weapons.
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But I doubt that the US would end up striking the Chinese mainland, because then you end up on the nuclear escalation ladder, and China now has enough nukes to credibly threaten MAD. Call it 250+ warheads capable of reaching the USA now. 3 years ago, there were less than 100? warheads.
You can see how careful the US is with respect to Russia.
My best guess is that there would be a whole lot of sanctions, but no direct military involvement.
