I think the exact opposite
O'Brien did a pretty good job as a hybrid right back and, if Branthwaite stays, you'd assume him and Tarkowski will be the first choice CB pairing so most of O'Brien's playing time will still come as a right back. Don't get me wrong, I want to sign a new right back as well, but Mykolenko's lack of ability with the ball is one of the major flaws in our approach play - a new starting left back is, to me, a bigger priority than a starting right back (though both should 100% be on the priority list this summer).