Whether it's just the manuscript or the finished product, at least the end appears to be in sight. It would take at least several months to go from manuscript to published book.

I know that some chapters he wrote for the previous book were moved to Winds of Winter. It wouldn't surprise me if at least some of the chapters he has written for Winds of Winter wind up in the final book instead. I agree it's better to read the books first and I've been avoiding the television series for that reason. I don't know if I can wait another 10 years for the last book though :).