Bucky Barnes, no matter which version of his character Sebastian Stan had excellently portrayed, is definitely one of Marvel Studios' most compelling characters, and his journey still carries on to new heights in the upcoming 'Thunderbolts' film.
When addressing the film with Entertainment Weekly (via TheDirect), Marvel Studios President Kevin Feige spoke of Bucky Barnes and the role he will take up going into the film as the ragtag groups "de facto leader":
"That's another one. We've got a lot of things that start shooting relatively soon. What's fun about that, and I sort of said this at D23, is that they are barely heroes. None of them would consider themselves heroes. When your de facto leader is Bucky Barnes, that's sort of all you need to know. That's the trickle down."
As previously stated, Bucky Barnes has always been an extremely compelling character; Winter Soldier or not. Anticipating seeing him taking up a leadership role with a group of misfits within The Thunderbolts team will be a different side of him Marvel can explore, after always having fallen in line as a partner.
He has always been there to support Steve Rogers, and Sam Wilson in 'Captain America: Civil War', 'Avengers: Infinity War', and 'Falcon and The Winter Soldier'. It is Bucky's loyalty and experience that will elevate him to inspire and lead The Thunderbolts team as the trustworthy figure they will need.