China has an easier time displacing Korean companies because Seoul occupies the lower end of the high tech value chain.The Koreans will be pushed out of the Chinese DRAM market the same way they've already been pushed out of the Chinese smart phone market and the Chinese automobile market and, increasingly, the Chinese display market.
The US is well known for ensuring that its "allies" are punished more than itself in any export control strategy. There's a reason the operations of US companies like Tesla and Apple haven't been really affected by the sanctions, while Samsung, SK Hynix, and the like have.
One thing I've noticed is that Korean companies, contrary to US companies, have a much harder time staying competitive in China, once they start getting actual Chinese competition. This is probably because Chinese consumers largely consider Korean products to be expendable and not symbols of prestige. Hence Korean companies are much more likely to lose the market permanently.
Consumer electronics are usually the first to be cannibalized as competitors climb up the value chain.