Alconbury, as an airfield, has been closed for some years. It must be at least ten years ago when I did some TV filming work there, in the underground Command Center, built at a cost of some £13 million, and closed within three years.
The HAS's were empty and starting to rot, and the runways were being used by 'Top Gear' at that time, before they moved elsewhere.
The field still had civilian, or perhaps MoD security gates, and the main gate and camp were still occupied by the USAF, but the airfield was disused.
Be a shame to see Mildenhall go, and as far as I know, Molesworth was similar to Alconbury, being used for storage, and, I think, with at least some of the housing being used for displaced persons, but again, it's some time since I passed Molesworth, so things might have changed.