Fair warning here; there are some spoilers regarding the 6th (last) and the upcoming 7th season.
According to Watchers on the Wall HBO filmed some scenes focusing on Theon and Yara Greyjoy, specifically these two characters in a sea battle. That is not news to anyone who watched season 6’s finale since these two sailed off with Daenerys in the last scene, but there is more. According to the Watchers on the Wall creepy uncle Euron will catch up with them and capture one of the siblings.
Euron is supposed to ally with Cersei to take on their common enemies, however, some theories predict that he might also still propose to Daenerys and try to make a deal with her.
The web site also reports that Euron will murder one of the Sand Snakes. Which one? There is no info on that. But Dorne became so boring in the show so it does not matter that much.
Game of Thrones will be back in Summer 2017.
And yes, that IS heart breaking.