I also think the reason he isn't saying anything is in case he hates it after it's finished then decided to rewrite 2/3 of it
God I hope that doesn't happen
I'm hoping it'll be out next December (plus it'll give D&D some time to digest the material for doing seasons 6 & 7, as well as include some plot points in S5 so it's not as boring as watching Brienne roam around or watching the Dornish and Iron Born), but we'll see
. I honestly believe that the writing process should be a bit easier for him for these last 2 books; the biggest issue he probably had with AFFC and ADWD (besides the 5 year gap and Mereeneese knot) is filling in the blanks/middle of the series before the shite hits the fan.