(Spoiler warning: the theory could contain spoilers for the upcoming Captain America: Civil War movie. Proceed at your own risk.)
Ever since the final trailer of the upcoming Captain America: Civil War trailer came out, Marvel has left us with a lot of easter eggs and tips on what is going to happen in the movie. Fans have been discussing controversial topics such as the apparent death of War Machine, the new Spidey suit, or the image of Ant-man on Hawkeye's arrow. But what I was wondering about is the metal arm of James "Bucky" Barnes, A.K.A the Winter Soldier. Previous articles contained a theory about Bucky losing his metal arm.
For those who do not know about the arm, it is a "cybernetic implant attached to the Winter Soldier's body to be used in place of his missing left arm", according to the Marvel Cinematic Universe Wiki. It is a metal arm that gives Bucky enhanced strength and can discharge an EMP causing electronics to go haywire. Worth mentioning is that the arm has a red star symbol printed on it, which could be the key to explaining the possible fate of the Winter Soldier.
Below are a few scenes that are related to Bucky's metal arm.
We see here in the post-credit scene from Ant-man where Bucky's arm is stuck to a machine, probably a vise. I believe he might be working on upgrades of his arm or he is just simply stuck by accident. While it has a low chance to be true, in fact this might be the reason why his arm was stripped of.
This is where we all see that Bucky's metal arm does not have a red star on it. He appears in the yellow tube, and has wires on him. Below are some more images where his arm does not have a red star.
But since appearing in Captain America: The Winter Soldier, his arm DOES have a red star on it. He still has it in the airport epic fight scene.
And here we see Bucky lying on the ground with his arm stripped of (there's the red star!).
Consider this: there are two scenes about Iron Man, Captain America and Winter Soldier fighting, and they are not fighting in the same place.
My theory would be that Bucky lost his metal in Epic Fight 1, which would be happening in the Raft, he goes back to the Hydra base for a new metal arm with no red stars. Iron Man confronts him and the three fight again next to the Hydra base (you can see the snowy mountains outside). I don's think he's going to die because Sebastian Stan still has a few movies contracts with Marvel.