If ever there was a lost opportunity with a USAF base closure it was Upper Heyford (on the M40 and mainline rail) or Alconbury (on the A1 and ECML).
EGUN catchment area is far too limited for significant pax ops surely too far from London to draw in traffic that would use STN anyway
Only reasonable suggestion might be turn CBG over to housing and relocate the maintenance/painting business and occasional bizjet traffic to Mildenhall.