If this is a pre-war economy, the US is screwed not because of AI but because we started a stupid trade war that's going to cut us off of our supply of dysprosium which is critical for defense manufacturing.
The USA and it's allies won WWII mainly due to superior production capacity. This advantage now works in China's favor. And the USA no longer has allies.
Bottom line: If China decides to take Taiwan, the USA will have to choose between either doing nothing or mutual annihilation.
It appears that China intends to make this abundantly clear to US "leadership" *before* they launch an invasion --- in hopes of avoiding mutual annihilation which neither side wants.
The US isn't going to get back manufacturing capacity on China's scale, and without real long-term economic plans beyond "bet it all on AGI", what they do have is going to be further strained. They can pump pork into the defense industry specifically, but probably not forever. You can't make a functional economy out of twelve fighter-jet plants and 500,000,000 hectares of unsellable soy.
So over time, you've got a defense partner that's finding it harder and harder to play World Police on a grand scale, and a trading partner that's less and less wealthy and able to dictate terms. Eventually, Taipei will pick up a BRICS application form out of self-interest.