I'm gonna say, I really enjoyed Gendry in this episode. Him making a warhammer like his father was a great touch. As was his meeting with Jon.
Little does he know that his father hated Jon's father.
In the episode 6 preview, it looks like Hound is using the hammer. I really hope Gendry doesn't die because I need him to get married to Arya and rule Stormlands.
Also, Dany's entire claim to the throne is based on legitimacy. If Sam takes the book to Dragonstone, and there's more to it about Jon, then would Dany bend the knee to Jon?
I think it will be Tyrion or Varys who figures it out.
Imagine if next season, Jon returns to Dragonstone, and they all bend the knee, and Jon has a look of shock in his face - like when they declared him KITN.