There was a character introduced in the last Ep that is very specific to that story line. And there is supposed to be some sort of "break the internet" type scenario that happens during the season and I doubt it was The Hound showing back up. It ain't more walkers, it ain't Hordor or and I doubt it will be any unexpected deaths of major characters either.
GRRM said it was a no go but remember that there have been lies told about this this show to the public before.
Well we (and Arya) assume Syrio died but we never got confirmation, there is a theory is that he's a faceless man, if not Jaquen himself.
- He's from Bravos
- Timeline wise, that would put him and Jaquen in the same area.
- How does Magic Sexy Jesus get locked up, thrown in a cell and sent to the wall...unless he wanted to?
- They both referred to her as a boy on their first meeting...even though they knew better, probably to put it in her mind to use it as a cover, which she did.
- We didn't see him die. (not today....not today)
In fact, when Ayra told The Hound about what happened he gave her the
at the notion that a skilled fighter would fall to Trant and a couple Lannister men.
He was givin them nikkas work....EASY. Could have killed them, but the many faced god hadn't called their number. Faceless men don't kill people willy nilly...
Even if you wanna run with the assumption that he died because Trant didn't...we've seen Jaquen "die" right in front of Ayra after drinking her poison and pop right back up behind her. He could have duffed all of them out and found his way to to the black cells on purpose, to keep tabs on his apprentice.
X 2
Maywaifer got diced up. Even Jaquen didn't want that work. 
Got his uncle murked b/c he didn't want his babies being catapulted. We have one Blackfish. He can always have more babies. 
