Perhaps, but even if that's not their original intention, a lack of integration and assimilation is what tends to happen, especially when numbers get larger and the need to actually interact with the outside decreases. It remains a problem regardless of the intent.
Have you had the pleasure of living as a minority in another country? I have. It's gREAT! Integration and assimilation does not happen when the home culture is not welcoming to them. Remember: Immigrants CHOOSE their new country purposefully and with GREAT consideration. They believe that there is something in "that place" that they can benefit from. If you are a guest in your neighbour's house and your neighbour welcomes you in, is friendly and hospitable, you will have good feelings toward them and want to spend more time with them. If your neighbour is not welcoming, feels your presence is an imposition and is SOLELY focussed on ensuring you obey the rules of his house (no shoes in the house, don't move the christmas diorama pieces), you feel that you are an imposition and you feel unwelcome.
It is silly to think that minorities will ever "stop" interacting with locals; they are almost TOTALLY immersed in the culture and experience of being an outsider. Also, if their new culture has been welcoming to previous immigrants, THOSE immigrants will shine a more positive light on the new culture on newcomers.
If we've experienced it, does it make our opinions on the subject more relevant?
Yes; it likely makes it better informed. It's like, experience gives you greater knowledge.
This does begin to happen at some point, even if there's no grand conspiracy behind it.
No, no it does not. That is fear based talk. SOOOOOO many european nations have had immigration from far off places for centuries, and yet their cultures thrive.
If they aren't prepared to assimilate and integrate to whatever extent they are able, perhaps they should live somewhere else.
So when you say "assimilate and integrate", what do you mean exactly? Because there are children bullying and teasing minority students for eating their ethnic food (and no doubt adults who do it too).
If it means "abide by the rules of the land", I agree. If it means they have to drop every cultural practice that is important to them, well, I disagree with that.