@dannygr214 said:

Would like to see them at least mentioned in an episode. Does anyone know why these story lines were just dropped?

Let's just say that AoS pursued other storylines ahead of Graviton and Deathlok did make a re-appearance during the Inhumans story line. He had a bit of an upgrade also. As usual Agent Coulson was able to use that trump card as an Ace up his sleeve.

Graviton is rumored to be resurrected but we wont know if that is something inside the Framework or in the real reality.

They've said they haven't forgotten and will go back to it but it doesn't make sense to do it in the framework when the real Quinn and Graviton are still out there. I'm hoping to God that Season 5 gets announced and that they use Quinn and the Graviton as major story lines and end Agents of SHIELD by bringing it full circle with all the loose ends.

@Hajikm26 said:

They've said they haven't forgotten and will go back to it but it doesn't make sense to do it in the framework when the real Quinn and Graviton are still out there. I'm hoping to God that Season 5 gets announced and that they use Quinn and the Graviton as major story lines and end Agents of SHIELD by bringing it full circle with all the loose ends.

I would be glad to see that. It would also reward and create an incentive for potentially new users to start watching previous season episodes.

The Rising Tide, Donnie Gill, Graviton, the pilfered 084's and other weapons from the Fridge, Fury, Deathlok, Akela Amidor, Armin Zola, there are lots of threads that haven't been pulled that could be quite rewarding for a season 5.