MCU Phase 4: 10 Massive Stories Marvel Could Adapt Next
8. HYDRA Reborn
Ever since he was evaporated in a shower of blue at the climax of Captain America: The First Avenger, the question of Red Skull's fate has been a pretty pressing one - particularly as the original plan was to have him return in some way down the line. Unfortunately, Hugo Weaving turned sour on playing the character and those plans were seemingly scrapped, as the Cap story moved away from him and towards Civil War.
While HYDRA seems to have been pulled down by the actions of the Avengers, there's no keeping such an organisation down (when one head is cut off, another grows in its place), and there's no way there aren't sleeper cells and secret factions still out there. And if Red Skull were to be returned by Thanos (accidentally), they would presumably spring back to life under his following.
It would be better to have Red Skull's return simply teased in Avengers: Infinity War or Avengers 4 rather than having him team up with Thanos (perhaps with a reveal that copies Thanos' own in The Avengers). And then for Phase 4 to see a new ferocious HYDRA rise once more, giving Bucky and Falcon something to do in the wake of Cap's expected death.