i think given the lack of young full backs and the amount of good young cb's that the french team has got, the 3 at the back system would be more suitable.
i don't fancy umtiti as a cb, i much rather him as a left sided player.  i think he has certain qualities that give him an edge in this position than kurzawa.
imbula is a player with a lot of stamina, half decent speed, decent passing and defending.  which makes him the only other player suitable for the wide position.
kondogbia will boss it in midfield.  so between that core of defensive players it would allow players like pogba, griezmann, martial and lacazette the freedom to attack, making france one of the most threatening teams in the competition