It was reported by a spoiler site that's been about accurate about every other mcu spoiler they've posted prior to the movie's release. But they did say that separate scenes with Bucky, Sam, and Sharon using the shield as the new Cap were filmed, similar to how three different secondary character death scenes are filmed. I do think that it's going to be Bucky, but I would still like to see the Sharon scenes at some point. I think she's going to be relegated to love interest in the movie tbh.