I would take Didier once all of the old guard on the team has retired. My opinion, wrong as it may be, is that these guys may look at DD more as a friend than a tactician, and I get the feeling that some might try to walk all over him for their own agendas.
I'm not saying that Descahmps isn't a good coach, but because he is still fresh in the minds of supporters as a player, then expectations for him might be slightly higher than normal.