I don’t see Coutinho anywhere other than the front two in your example . There is no way Coutinho could have put the shift that Buendia put it, he doesn’t have the legs for it. Buendia and McGinn were basically playing as wing backs in the back 6, no way Coutinho could have done that.
He could take the place of Bailey in the current system, versus a low block. Other than a complete change of shape (which wouldn’t surprise be with Emery), I don’t see where else he fits.