If the cable is guillotined and the cable hung up, then the procedure is to fly a tight spiral over the field aiming to land in the centre. I know someone who did it for real once, he says it was no big drama.
Once, I did see the cable get struck by lightning before the glider released. The glider pilots were aware what had happened, but the winch driver just thought it was a cable break. However, the cable couldn't be found. It had vapourised!