That was an early version of the climax, but it eventually changed when the Russos decided to streamline the story and make it more about the hero-on-hero combat.
It sounds like in its original incarnation, Captain America: Civil War featured a bigger brawl between the heroes and the squad of highly-trained Winter Soldiers hidden at the Siberian outpost.
Talk about a drastically different version of the story.
However, as Scott Adkins noted during his appearance on the Empire podcast, he did eventually get to star as a henchman in Doctor Strange instead (which led to him kicking Benedict Cumberbatch in the chest), so he can’t be too upset about the whole thing.