I think they will absolutely intervene. The sentiment in the US against china is really negative...
US and Europe align within a few % when it comes to anti-China sentiments. US is 7th after Japan, Australia, Sweden, Denmark, UK and South Korea.
On the other hand, given current US political status, they might actually want a war despite the risk.
"Negative sentiment" is not cause, it's propaganda for the possible declaration of war.
If China invades Taiwan, US will defend it*
You would need to ask China if it's worth the trouble.
* that is if China doesn't fail as miserably as it did with Vietnam where it declared victory after retreating