Don't get me wrong: I'm not going to be like one of those idiots who tries to convince you that war is good for an economy because so much stuff gets destroyed that there's lots of money to be made rebuilding it.
War is bad.
Trade war is a perverse form of war -- one in which regimes purposely harm "their own people" with tariffs and other trade restrictions, making "their own people" poorer in hopes of also harming their opponent regimes. There's nothing morally right, practically beneficial, or non-pea-brained about it.
BUT!
Even the worst ideas usually have at least some silver linings.
The one I'm thinking of in this case is: Smuggling.
If tariffs are high enough and/or restrictions are onerous enough, smuggling can be good business. Higher tariffs mean that you can charge higher prices and still under-sell the "legal" market. Tougher restrictions mean you can sell goods people want but can't get on the "legal" market.
If consumers have to pay $1.00 for "legally imported" widgets of a reasonably popular kind, but can get "smuggled" widgets of that kind for 99 cents, there's going to be a market for "smuggled" widgets. Likewise, if they can't get those "legally imported" widgets at all, there will be a market for "smuggled" widgets.
I'm an odd duck in that I'd rather pay $1.01 for a "smuggled" widget than $1.00 for a "legally imported" widget on principle, because I'd rather give smugglers additional profit than give the government a rake-off.
Most people aren't like me ... but most people are trying to get by, which means that the longer this trade war crap goes on and the worse it gets, the bigger the gray/black market will become. Probably not good enough to make the tariff/trade war crap economically "worth it" by completely collapsing the regime, but at least a nice partial offset to the regime's fuckery.