Kounde is a RB atm, regardless of what he once was or what he was bought for. He isn't big enough or athletic enough (jumping ability) to be a starting CB in a big club.
He was a perfect fit for Xavi's ball as a defensive RB, for Flick he is a decent fit when he is in form, which only happened in the second half of last season. When he isn't, he isn't good enough regardless of fit as he gets cooked on both ends.
Barca is allergic to selling and reinvesting strategy, and the market for fullbacks is awful atm, and many of those are system RB. One that fits one system could struggle in the other.
I don't see us replacing him in the next few years, if anything he ismore likely to be Our starting RB in 2030 than being replaced in the summer.