For future reference the giant trade deficit has benefited the USA enormously and increased quality of of life of most Americans. The incredible thing here is not that we import so much from China but that the hyper-productive Chinese exporters and manufactures have been so willing to surrender real goods and labor for the green pieces of paper we call currency which the government can create at the push of the button. This was the trade of the century.
I suspect that this will ultimately only help China and hurt America. China will be forced to develop their own internal markets and diversify their exports more -- which they've been doing already. You'll also just see more action from other low wage exporters like Vietnam. In the end Americans will just as price increases. Tariffs won't bring back jobs, reduce the extreme inequality that's killing the country nor are they real investment.
The goal of the tariffs is of course not to stop that trading. The goal is just to pick up some free money under the assumption that China will not dare to start a trade war.
The US stands to lose all of the manufactured (especially electronics) goods China makes. The supply chains for a lot of its companies (especially tech) will be severed. China stands to lose soybeans, civilian aircraft, corn and... chicken feet, I suppose?
Of those, the only one that isn't easily substitutable with imports from elsewhere is civilian aircraft, and China is already pretty far ahead on making its own.
I think, on balance, given the relative substitutability of US vs Chinese imports, China has the upper hand in a peaceful scenario. The US can't really replace the Chinese industrial ecosystem whereas China can get corn and soybeans from elsewhere - assuming that shipping is not blocked.
...which is why I'm worried that the US might try to escalate a trade war to blockades and from blockades to, well, you know...
That said, if the US continues with a policy of unfettered trade while China continues with managed trade, China's hand grows stronger while the US's gets weaker. The US doesn't actually have a lot of good options now - it's about 15 years too late for it to safely reverse this process.
China will certainly notice that, but in the long run the U.S. will certainly lose more from that decision: The heavily (illegaly?) subsidized U.S. agriculture will get a hard hit, as will every industry that relies on Chinese components, from smartphones to cars. It will be a boon for the other continents, though, as their companies will gain market share, because the U.S. products will have to be sold at higher prices.
Sanctions hurt people on both sides. For example, is a company in California has phones made by a contract manufacturer in China, imports them, and reexports them all over the world at steep prices, who's hurt most if the volume of that trade is limited?
I don't like trump at all. But I agree with defending our country. And overall, the less we can rely on China the better.