Season 6 General Speculation v10

We still don't know if in the show Sam and Gilly go to Oldtown briefly before Horn Hill and then returns to the citadel afterward or if Sam doesn't go to Oldtown until after he leaves Gilly with his family.

We're only 3 weeks away now!   

I thought he could be the young lord Cerwyn, but in the casting call that role only filmed in December. According to this guy's twitter, he was already filming in August. 

I agree. Every indication we have is that Euron will not be ready to start his move on Oldtown until the very end of the season. So Sam arriving in Oldtown to settle much before that happens won't really work as the Ironborn invasion of the Reach had already started when Sam arrived in the books. So IMO Sam will touch down briefly when his boat lands, talk to a random novice, then move on right away to Horn Hill, saving his actual settling in Oldtown and the introduction of the important Oldtown cast for season 7, corresponding to Euron's assault on the city.

Though looking back at the casting calls he could as likely be "Bower", one of the three Sympathizers or Rickard Stark. So I guess it'll be pretty hard to narrow this down accurately. 

I guess they've made room for that now. This seems like the most the show's expanded since s3 which was probably the busiest season storyline-wise but I think they've learned their lesson from s2 and s3 which imo were pretty cluttered in their pacing and will pace things more like s4, where some storylines (Sam's being the most notable example here) will only appear in 3 or 4 episodes at most to make room for certain expansions on certain fronts. And then by the end of the season enough of these story threads will have merged that it can have pacing almost like s1 had, where huge swaths of major characters are actually together and joining and meeting increasingly rather than apart and often separating. 

Just in terms of Main Characters
Beginning of the Season
Beyond the Wall: Bran
Braavos: Arya and Jaqen
Dorne: Ellaria
Dothraki Sea: Daario and Jorah
King's Landing: Bronn, Cersei, Jaime, Margaery, and Tommen
Meereen: Missandei, Tyrion, and Varys
Road to Castle Black: Brienne, Sansa, and Theon
Road to Vaes Dothrak: Dany
Sailing for The Reach: Gilly and Sam
The Vale: LF
The Wall: Davos, Jon, Mel, and Tormund
Winterfell: Ramsay and Roose

This is mostly speculation for some characters at least. 
End of the Season
Beyond the Wall: Bran
Dorne: Varys
Horn Hill: Gilly
King's Landing: Cersei, Margaery, and Tommen
Meereen: Dany, Missandei, and Tyrion
Oldtown: Jaqen and Sam
The Riverlands: Arya, Brienne, Bronn, and Jaime
Volantis: Theon
Winterfell: Jon, Sansa, Davos, Mel, and LF
I'm not really sure where Jorah will be, but I think he'll be alive. 
Daario, Ellaria, Ramsay, Roose, and Tormund are likely to be dead by 610.

So it's definitely starting to condense a little bit. 

I'm more in the Varys-will-be-in-KL school of thought myself and at this point think Yara and Theon will be in Meereen or just off-shore of it in the finale rather than still in Volantis. But yeah, for the most part that's a good representation. Which will allow s7 to be all the more confidently-paced. Particularly as essentially ALL storylines begin to intersect around KL and the North, as I think will have happened by the end of s7.

And we can probably exclude Gilly since it's highly unlikely we'll follow her life at Horn Hill. Maybe she takes a season off next year, who knows?

But yeah, episode 10 will probably cover Oldtown, King's Landing, Winterfell, The Riverlands, Meereen and just a bit of Dorne as season 7 set-up.