If all your neighbors no longer spoke English, you don't think that would affect you?

Obviously that's an extreme example, but other cultural differences will affect you as well.

If they all spoke a common language, I'd try to learn a bit of it. How exciting!

It's also exciting to experience ethnic clashes between rival groups of immigrants[1].

[1] https://toronto.citynews.ca/2024/11/03/violence-at-hindu-tem...

"Wow all these Goths have moved into my town, but they don't speak Latin, they speak Gothic. How exiting!"

- Anonymous Roman Citizen, 412 AD

It can be a really cool thing too if both cultures open each other to exchange languages and celebrations, but it requires a lot of effort from everyone.

No, I don’t. This is already the case in many neighborhoods in the USA and the sky isn’t falling in those places.

Also, I live in Germany half of the year, and there most of my neighbors don’t speak any English, and my neighborhood is fine. I don’t see the problem you are describing with your example.

If that’s your “extreme” example, I am curious what your day-to-day ones would be.

Perhaps it’s uncharitable but I am having a hard time seeing how this doesn’t alias to simple racism.

I didn't claim the "sky would fall". I just claimed it would affect you.

I think most would agree that it is easier to form connections with those who are more similar to oneself. Call it racism or tribalism if you want, but that's reality.

I think it hijacks the local culture, there's probably a better word, but I'm no native.

It's mind boggling you are denying the fact that having many people from the same group clustered in a "multicultural" environment has no impact on society has a whole. Of course it does, this is why we have laws protecting minorities, it's irrelevant how the majority is established (either per-existing or minority suddenly growing), the impact may be positive but it's naive to assume it will always be so.