Oh that's easy: as soon as China gets good enough to compete at any market seen as vital, "the west" either makes up some nebulous national security threat to cut them off or imposes high enough import taxes to make the home-made versions cheaper in comparison. The same way "the west" has done it with cars, phones, and social media in recent years.
There is no free market competition between "the west" and China, they're two completely separate markets for a reason. You're only allowed to cross that isle in a limited capacity, as soon as you get big enough to be seen as a legit threat, you're getting cut off. Works both ways, Tesla can sell in China, but they can't beat BYD. Apple can sell iPhones, but only because their market share is not big enough to matter.
There is no free market competition between "the west" and China, they're two completely separate markets for a reason. You're only allowed to cross that isle in a limited capacity, as soon as you get big enough to be seen as a legit threat, you're getting cut off. Works both ways, Tesla can sell in China, but they can't beat BYD. Apple can sell iPhones, but only because their market share is not big enough to matter.