In response to RaP's comment:
There are organization dealing with this. In fact when I was in Boro Park this past year - at least once a week an appeal was made for such organizations in the shul of Rav Menashe Klein where I davened every day. They were specifically for chassidic youth.
Workers in these programs in American told me that 70-80 per cent of the members of these programs have been abused.
There are programs here in Israel also. I remember once - several years ago - a rav who runs one of these organizations made an appeal in Rav Sternbuch's shul and noted that the Chazon Ish said that it is not necessarily the nebach but in fact it was the brightest and best adjusted who went off the Derech.
I also once was visiting Rav Shlomo Zalman Auerbach with a friend of mine whose father was a very prominent rosh yeshiva in America - but he had become a Breslavor chasid. When Rav Shlomo Zalman heard the name of his father he literally jumped out of his seat. I later asked my friend why he had reacted that way. He said, of the yeshiva class of Rav Shlomo Zalman at Eitz Chaim - most of his classmates when off the derech. It upset him to see that I had not followed in my father's path - not that he had a problem with Breslov itsef.
Finally Rav Menachem Porush's son - who is involved in politics and social action - once mentioned at a conference on the subject the following.
"It is not that we have more drop outs than in previous years. The issue is that in previous years the drop out left the community - 'he went to visit his aunt in California.' However today the drop outs are kept in the yeshivos and beis yaakov's and where they are a corrosive element to the others students."
A friend of mine noted that Meah Sharim has retained basically the same number of apartments for a hundred years - despite the fact that they have always had large families. He said this was primarily due to the children going off the derech in large numbers and leaving the community.
So yes there are families who kick out there children when they go off the derech- but there are also many who try to keep them in - sending them to special yeshivos to try to help them. Har Nof itself has a number of seminaries and yeshivos which deal specifically with this problem.
BTW Rabbi Greenwald - as well as his sons are recognized experts in dealing with this problem in the Chareidi world and their services are definitely being used.