.. and I tend to agree. She'll take the boat in s4's finale, IMO.

The actors reported to have filmed (because they've been spotted or have posted about it on Twitter etc.) the first week include the one playing Melisandre, and they were at the locations standing for the north/wall etc. So they're moving Stannis' arrival at the Wall ahead, as s3 let believe they would.

That makes Gatiss more likely to be involved in the Wall (new character in the Watch, or a wildling) story lines, or perhaps in Bran's arc as they'll no doubt use the same areas for Bran's scenes, and it would make sense to film his scenes during the summer school break.

Mind you, it's not that meaningful as they had to film Gatiss's scenes while he was still on break from Sherlock, and both the Kindly Man or the Three-eyed Raven bits would likely be filmed in studio rather than on location.

The schedule reported, if it's accurate, more or less makes it very unlikely he's playing a part in King's Landing or the south (eg: Mace Tyrell) or someone new in Dany's arc.