Even if they send them off at age 11 or 13, their spending the formative years of there life with no experience in a frum community.
I think not enough kids brought up in such homes have reached adulthood yet for us to see what happens. My prediction would be that they will not frei out, but that they will be really visibly weird and different if they try to live in a normal community.
My big question is how those kids could go on to become shluchim themselves. The whole point is that someone from the religious world brings a taste of that to the outside. If you’re raised in a “hick town” and them become a shliach there, how are you going to answer questions about living in a frum community? You’re just as inexperienced as the chilonim.