As you said, Merkel is stepping down, nobody know who is going to be the next czar. Remember we are so certain that europe won't boycott huawei? Never underestimate the yanks' influence on EU politicians and media. The US has allies in EU parliaments and media. While US has poor reputation today in EU, but they are mostly because of trump. Now he is gone, Biden has a chance to reverse that. Public opinion is fickle anyway. Let's be real, while US reputation is bad in EU, China's probably even worse.

EU joining the US in xinjiang issue and south china sea issue, to me look like a theatrical show to show the world that EU govs still care about human right, and that they are still put great value on relationship with the US despite EU attempt to steer a more independent policy. The effect of EU actions both on xinjiang and south china sea issues to China are minimal. Slapping sanction on 4 regional officials and sending one or two ships to sail in south china sea, won't affect China much. But it seems Xi is indeed want to stop this charade once and for all by reacting extremely harsh. It might stop the EU nagging, but it could certainly push the EU towards US camp. It weaken the hand of EU officials that want closer ties with China and set up independent EU policy, free from US.

Whether this is a correct strategy for China, I can't say. Maybe it is time for China to chart new and more hawkish foreign policy to defend Chinese national interest. But if that is what China's strategy is, then China better prepare for more economic and tech blockade from the west. I'm actually surprised that Chinese ambassador refuse to heed the summon by EU. It is a bit of breach of protocol, I think. Certainly very undiplomatic and could have big repercussion on the relationship. There are better way to address this summon, China can also summon EU ambassador to show displeasure.

But again, I don't know if this is the right strategy. It seems, since trump, the world is heading into uncertain global world order where there is no rules, not even on superficial level.