The 100 pages is mostly material he moved from ADWD. He said that he's planning on starting the real work on TWOW in January. I hope he can wrap it up in two books, but I'm now skeptical. He has close to 30 open plotlines to deal with. Maybe a war with The Others or a greyscale epidemic courtesy of Cniington will thin the herd a bit. It actually might not be a bad idea for him to go back to his original plan of a time gap between books. A couple of years would do it, maybe even just 1.
That would be very disappointing if he had a mass killing from grayscale or the Others... But I don't see how he going to do it in two books... Maybe he can pull it off if he don't describe everything in everyone's plate... And we don't have to read about how spicy the seasoned beef is today... Or how horny Dany is or how bad her feet hurt in golden sanders...
If the other books are like ADWD, he will need about 20 more books to finish... But at least everyone will be master cooks and fashion Gods...