> we import more from them than we export.
What that means is a trade war is going to cause prices in the US to rise more than prices in China. Which means either the prices of what the US does export will go up or the USA's standard of living will go down.
In the short term a carefully crafted trade barrier can have positive effects. For example, if the government decides a country should have natural advantage in industry X, but establishing industry X is impossible because of foreign competition than a trade barrier is a reasonable option. In effect the rest of the population is subsidising the initial higher prices and poor quality from industry X until experience and effects of scale kick in.
The danger is a trade barrier can be damned hard to get rid of because inevitably doing so will kill jobs. So hard that killing them it usually requires some sort of crisis. That's what happened in both Australia and NZ a few decades ago, with one Australia treasurer famously saying "if we don't do something we will become a banana republic". The barriers came down, there was an enormous amount of pain (interest rates hitting 20%), and he got voted out. But the country hasn't had a recession since.
If Trump's little war disappears with Trump I doubt it will have much effect on anything. If I was a US citizen, the most worrying line in that article is some democrats support it, so they could stay.