I don't think it's a good idea to nurse this idea for the following reasons:
1. I don't believe Taiwanese want to be part of the US. They already have their own country.
2. The US shouldn't counter the Chinese imperialist ambitions of annexing Taiwan by doing something that could be viewed as the same thing.
3. It's not really necessary for what you want. The US could enter an open alliance with Taiwan if it wanted to making a Chinese declaration of war against Taiwan a declaration of war against the US.
4. The US should make a stand that the independent country of Taiwan has a right to exist and support that right alone not precondition on joining the US.
I could go on, but I think this "Taiwan becomes a US state" thing that I see repeated a lot is just plain silly.