According to the following article (in German), 15-year-old Sabina and 17-year-old Samra from Vienna, who went of to Syria in search of "Jihad" in April have made contact with their parents, saying they want out and to come back home - although experts say this is well nigh impossible at the moment:
http://www.rp-online.de/panorama/auslan ... -1.4584257
There is another factor that may come into play - a collapse of morale in DAESH ranks. How cold does it get in winter in that region, I wonder?