The thing is that changing the igl every time is bad because u need to play with the playstyle that he is trying to develop and because of that it takes more time than u expect to play as u want to play with his system.
NBK as an Igl is the first option, but apex can be a good option too.
since rush is their new entry he isnt that good as we expect from him to be with entrying and because of that they should move him back to supporting and letting apex to entry while tarik is back to igling, auti to lurk and ska to awp.
this would be good because apex has an agressive playstyle and he can play actually good when he has those guys from his back telling him what to do.
but what about their english ? would it destroy their communication between the french guys and the americans ? especially since nbk would be their igl if he would join, i think that it can destroy some calls between them and confuse them mid round, which could suck but they need to think about that.
and because of that i think that apex would be a great choice unless nbk's english is good