Practically neville, kids of shluchim go to winter camps, summer camps, and kinus together, and summer camp with mainstream kids.Also once they hit high school or Yeshiva, they often go away and dorm in the regular schools. So they’re not cavemen to the regular community.
When I taught in beis Rivkah fifth grade, I had a girl in my class for a week from a far flung community in Canada. Her parents send her to beis Rivkah in CH every year for a week or two so the transition won’t be difficult by high school as shell be familiar with each other. She’s not the only one.
In addition nowadays shluchims kids go to online school together and receive an excellent chassidishe education. In fact, some of my classmates in ninth grade came straight from online school and they were on par with us, and in some ways even advanced.
So educationally they’re fine. Socially the shluchim do their best for their kids as some examples above. Some also will send their kids to the local Jewish school for the secular studies just so they develop social skills, and teach them kodesh at home. Every family sees what their kids need and do their best for them. Bh now there are more resources than ever with online school and conference calls etc then ever before.