Well, given that A400M is designed with soft-field operation in mind, it must be a pretty tatty transport base that's being closed - unless it just operates helicopters or similar?
More likely that the hangarage would need improvement to accommodate the A400M on the rare occasions it needs to be inside.....
The European Staff Requirement was accepted by all customers - if the GAF base wasn't adequate for that, then it's hardly any fault of the A400M!