I fully agree that a country should only accept people who are willing to learn from their surrounding and adapt to the local culture instead of being hung up on their archaic traditions.
At the same time I believe that with steadily rising standards of living and with new advancements in technology, especially in transportation, globalization will march on and would become an even bigger force. It‘s only a matter of which cultures would in the end dominate the world since global culture would eventually homogenize. When a culture is perceived as „cool“, people tend to adapt it. That‘s how American culture became wildly popular around the world. You take a middle class person in early 2000s almost anywhere in the world bar for ultra-conservative societies, he/she would ve compatible with the American culture and would have made an excellent citizen there. Growing up in early 2000s you had TV shows, movies with leads belonging to all sorts of ethnicites. Yet, none of the nonsense talking points of „woke“, culture wars etc. existed back then.
The problem that you see nowadays on one hand is caused by a demographic that got rich all of a sudden and who are not exactly used to their higher standards of living. For example, I had an Indian guy tell me that even Pasta is a luxury where he comes from. It takes time for these people to get used to a modern lifestyle and just like that the current trend of immigration phobia would disappear as these poeple learn to behave better. On the other hand you have ultra-conservative ideologies coming from the MENA region which I think would also disappear as it happened in Iran. So long story short, IMO these problem are temporary. One should be careful before making long term doom and gloom predictions based on the curent state of affairs.
Now when it comes to China, it now has an unique opportunity to be one of the most dominant cultures across the globe just like American culture and it‘s beyong me, why anyone would miss up on that opportunity.