Not to worry!
No American administration is going to fight Red China.
When (not "if") the Emperor seizes Taiwan and massacres the first democracy in Chinese history, the West will loudly bemoan the action.
Then the next day the West will resume making tons of money by dealing with Red China.
Hear tell, there's a debate now in Taiwan: fight back as the Ukrainians are doing or surrender and avoid useless and traumatic violence?
I hope the United States will have the guts to at least tell the Chinese tyrants to hold off until this country can evacuate (by air and sea) as many Taiwanese as possible (to the United States, Australia, etc.).
And, of course, the United States should encourage Japan to once again build up a strong military deterrence to the Chinese menace.