I'm going to piggy back on your theory.

Holland Reed (Meera's father) is the Lord of Greywater Watch - a castle built atop a man-made island that moves - making it undetectable. This has obvious advantages because Bran will need to remain in hiding as long as Ramsay Bolton rules Winterfell. However, you mentioned the Isle of Faces, and this is extremely important for two reasons.

1) The island is full of Weirwood Trees, which would give Bran a great access point to be able to see what is going on everywhere at any given time, past, present, and potentially even future. Jojen (Howland Reed's son and Meera's brother) had Greensight, and was able to catch glimpses of the future. And so, by meeting up with Howland, and getting to the Isle of Faces, they will not only have Weirwood Trees to use, but they may even take counsel with the Green Men; something which hasn't been done since when Addam Velaryon flew there on his dragon - unless Howland Reed did during he tourney at Harrenhal. I believe that Greensight and the Green Men are linked, and if this holds to be true, Bran will be taught or given the gift of Greensight, either through him warging into a Green Man or by bestowment.

2) The second important reason is that because this is where Howland Reed went during the tourney at Harrenhal, the story of the Knight of the Laughing Tree will come up again. And what I believe is that when Bran goes back in time to see Howland Reed at the Isle of Faces during the Tourney, he will take control of Howland's past body and fight for him during the tourney under the guise of The Knight of the Laughing Tree. Which will finally solve the mystery of the identity of the Knight of the Laughing Tree.