Airbus' intention is for 85 days maintenance over 12 years for the A400M.
Can the C17 or C130J match that?
It may be a pipe dream at the moment but I imagine that they will get pretty close to it. The hours flown will be nothing like a civil airline operator and some Airbus' are doing two years between C Checks.
If they can achieve that then the running costs will be quite favourable.