With Avengers: Infinity War being the culmination of 10 years of storytelling from Marvel Studios, focus was on Thanos and his assembly of all six Infinity Stones. Basically, everything built to this showdown, with the Avengers, Guardians of the Galaxy, Black Panther's forces in Wakanda and Doctor Strange, among the many sprawled across the universe to thwart the Mad Titan.
Due to the Russo brothers having such a huge cast, it's no surprise certain plot beats previously set up, as well as characters, would fall by the wayside. One of the more noticeably absent heroes was Emily VanCamp’s Sharon Carter, the love interest of Steve Rogers as of Civil War. While some romances were touched on -- Wanda Maximoff and Vision, and even Bruce Banner and Black Widow -- Sharon's didn't make the final cut because, well, there wasn't room for her and Steve's story.
With Chris Evans' poised for his swan song as Cap in Avengers 4, fans are wondering if Sharon will fall into the abyss currently hosting Natalie Portman's Jane Foster. However, just because the star-spangled Avenger's story ends doesn't mean Sharon's journey has to as well.
“Sharon Carter was a victim of what we came to realize as we were writing it,” writer Christopher Markus explained, “which is that, if you’re writing scenes that set up people before the story has gotten to them, such as Steve and Sharon trying to make it work in an apartment, they’re gonna go because the movie does not have time to catch up ‘previously on the life of Steve Rogers.'”
Whether Cap gets killed or retires, if the Marvel Cinematic Universe decides Sharon's story should end there, it would feel like she's a throwaway character, someone who's being sold short. In the comic books, however, she's been one of the biggest names within S.H.I.E.L.D., even acting as Executive Director briefly in Nick Fury's absence. This provides the perfect canvas for her development in the MCU's Phase Four.