Would be very interesting if they go that route.
A lot of the die hards feel some type of way about it as it diminishes Klaw's involvement in T'Chaka's death and potential lessens his status as a villain (not to mention that's not how it goes in the comics). I don't blame them on that one.
I say if Marvel plays it right it can work. Make it that winter soldier is the trigger man (Part of his many missions across the world), but Klaw is the one who schemed the whole plot. Considering how thorough T'Challa is, he would go after both the muscle and the puppet masters. Winter Soldier for civil war, and Klaw for his solo film.
I was going to say that if WS is the heir apparent to take over for Chris Evans as the new Captain America it probably wouldn't do for WS to have actually killed another future Avenger's father. Maybe Klaw did the deed and set up WS to throw BP off his trail?