IMO if Danilo can refind his Porto form he'd be exceptional as rotation for both the RB and LB position, he basically has no weak foot and can play on either side which should be a massive bonus, in his Porto time he also had the ability to play in midfield which albeit he didn't do much or at all he could during games tuck in.
He also began to get going for Madrid towards the end of the season so there's that aswell.