You seem well-read so I’d love to hear your thoughts on this:

How can people preserve their culture when faced with massive immigration? For example, Japan is about 99% ethnic Japanese right now. What happens if that changes to 50% Japanese and dropping within a century (Japan has famously low birth rates)? That’s the scale of the demographic changes that Western countries are on track for by 2100, and that’s without open borders. It would obviously be much more dramatic with open borders.

I agree with you that open borders are morally and economically correct, but it also seems obvious to me that it would overpower the original culture. After all, it’s hard to justify asking a new immigrant population to respect the existing cultural norms (like a Swede respecting local culture in Yemen) when the immigrant population is an increasing majority. If anything, the original population will be assimilated into the immigrant population, especially if they’re massively outnumbered (as would happen in Western and Eastern countries besides China if open borders were implemented).