Dorian Martell's son

Hodor 

11 minutes ago, Lost Melnibonean said:

Or Daario. 

Dario and euron aren't dead yet, but Aemon did in fact die on a boat and sam talked about him spending time on the deck of the ship. 

On 8/26/2016 at 9:41 PM, Zulaica said:

This is definitely Aeron so he will die most likely after witnessing whatever unfolds in the next chapter. Then we will probably see Euron's attempt on OldTown by Sam.

Or it is Maester Aemon sailing to Braavos. The smoking tower can still be Euron in Oldtown