1) Bucky As A Secret Weapon…For Good Or Bad
Bucky Barnes getting encased in ice at the end of Civil War by no means signals Sebastian Stan’s exit from the franchise. The erstwhile Winter Soldier only allows himself to be frozen for as long as he remains brainwashed, but he still remains a powerful individual, hidden away as a secret weapon, until Cap or any of the other Avengers might call on him again. And that’s only if they get to him first.
In the wrong hands, Bucky is still highly dangerous – and who’s to say he won’t be found and again reactivated by one of Marvel’s many bad guys? By keeping him alive, the Russos hint that Bucky will return to the MCU in the future. And as he has been before now, he could be either a force for good or a force for evil. Like Zemo, Bucky has most likely been put on ice with the idea of bringing him back for a later movie.