I have read that the USAF has had such serious parts issues with the C17 that the Air Force itself has resorted to 3D printing their own parts. Also, it seems the last preferred option for a C17 restart was for an aircraft with somewhat different fuselage dimensions (narrower by a meter, taller and some changes to door and ramp configurations). To wit, the next iteration of C17 could be identical to current or it could be modified enough to think twice.