Also read online that HBO confirmed that Season 4 with start on March 30th and that David and Dan said they think GoT will need 8 seasons total (so 5 more seasons) to tell the story :nana:. I agree with the 8 season approach because TWoW and ADoS are going to need 3 seasons.
Here is my breakdown:
Seasons 1-3 were AGoT, ACoK, and 2/3rd's of ASoS with a dash of ADWD Theon
Season 4--Remaining 1/3 of ASoS, start AFFC, continue the Theon ADWD story and get into ADWD with Bran, Dany, Davos
Season 5--Finish up AFFC and ADWD
Season 7--Remainder of TWoW, start ADoS
Season 8--finish ADoS and thus conclude ASOIAF