I don't think they'll keep using European-built batteries when Chinese-built batteries are readily available at a noticably lower price, perhaps 5 years from now unless there are e.g. tax penalties in place for owning a car with a battery made with co2-polluting power. Consumers will go for the car that's 10% cheaper.
This really does not hold up anymore. The idea that China is magically much cheaper despite the very long transport route is simply no longer the case.
Labor cost of the type of labor you need is already not that different from Europe. Energy can be more expensive. And the supply chain for so many batteries becomes a real issue.
Historically we have seen Tesla move from Japan produced Panasonic cells to Nevada produced cells. And this is pretty much universally considered a fantastic move by Tesla.
It is already the case that pretty much all large battery makers, including LG, SK from Korea, CATL from China, Tesla from the US and multiple new European producers all have announced gigantic investments to build cell plants in Europe.
Tesla is basically moving to a model where the battery factory and the car factory are basically in the same building or next to each other as localization is actually a huge cost driver.
See this map for the amount of localization being done:
