Unlike Fred I wouldn't see him as someone I'd trust to play that far back, the things I've watched Nice (admittedly more to see how Mario was getting on), he's been the happiest of the middle 3 to hang forward when they've lost the ball and he hasn't pressed either. Atsa(?) and Mendy seem the closest in their team to our pivot role.
Fred on the other hand gets stuck in all over the place pressing and chasing back, I'd have no worries about him taking Dinho's role, as long as Otamendi and Stones were briefed on headers.