Another details from the elf fair that proably interests most of us here: GRRM not only said there will be no gap, but also said parts of AFFC set in Dorne and the Iron Islands overlap with ASOS. That should have impact on the speculations about the new POV. It must be someone in Dorne unless the Theon POV is revived and the prologue is set in Dorne.
[Note: The information immediately below is a response to probing concerning the exact wording with which Mr. Martin conveyed the information mentioned above.]
I believe GRRM said parts of AFFC overlap with the previous book after explaining about the end of the gap idea and mentioned the Iron Islands and Dorne. So the plural can refer to both these aeras combined.
GRRM said at the fair that he will start to work on the second Dunk and Egg story after he finished AFFC. So this can't be the main reason for the delay. I didn't understand the title clearly, but I think it is going to be named "The Sworn Sword".