In order for Trump's threat of tariffs to be effective, with the Chinese or others, he must be credible for following through. Otherwise it is perceived as a bluff and he loses in the negotiations and his reputation suffers.
A prime example of a brinkmanship failure is Obama and his infamous failure to enforce the "Red Line" in Syria. Contrast that to Trump who reversed that failure at the very start of his Presidency. By launching Tomahawk Missiles against Syria without hesitation after another poisonous gas attack, Trump immediately earned "street cred."
Trump leveraged his negotiating credibility and the tactic of brinkmanship in negotiating the USMCA trade agreement with Canada and Mexico. He did the same with NATO and N. Korea. Those were all important in their own right. But they were also a setup for his next and tougher target, CHINA. And ultimately, for what's to come with the Israel and the so called "deal of the century."
The Chinese are tremendous negotiators. They turn brinkmanship into a game of chicken. By raising the stakes, as they typically do, they scare their opponents into backing down. It has worked for them time and again. But Trump is a different negotiator and leader than the Chinese have had to deal with before. He is predictably unpredictable - which drives them crazy. By they same token, I suspect they respect Trump the way they respect Sun Tzu (Art of War.)
The China trade negotiations are extremely significant and important. The USA has to protect it's intellectual property and cyber security. The outcome of these negotiations will have profound impacts on both of our economies and the world. The USA can not afford to fail. Trump knows that. He has spoken passionately about this for decades, long before he ran for President. He is not going to let America lose.
I don't know if my thoughts fall into the category of sanguine. I think of my view as pragmatic. Both the USA and China need one another - we both need a deal. Which one needs the other more is debatable - and it is akin to chasing one's tail. Or arguing who would win a nuclear war based, based on the number of missiles.
Some say time is on China's side. And, the fact that Xi doesn't need to win an election let's them wait us out. There's so many arguments, pro & con, on behalf of who wins a tariff war. But I don't believe China flew over this time to save face. They flew over because they want to save the deal. They are testing the boundaries of the deal. Trump said we're in "no rush to make a deal." That was the smartest thing he could have said. The tariffs hurt everyone .... but once a USA a manufacturer moves sourcing out of China, Xi knows it is hard to get it to go back.