TK will not rebook to other airline for a delay of 6 hours. Forget it.

It doesn't really make sense to arrange for accommodation as a delay of around 6 hours or slightly more, will not give you any time at a hotel (hotels are located far away in Istanbul city). It needs to be at least 9-10 hours before it make sense. TK doesn't provide accommodation at the airside (and very expensive) YOTEL.