There's a 99 year lease on the runways which was agreed between Scottish Aviation (now British Aerospace) and the then Ministry of Aviation in 1953 which ensures that the runways are kept should the tenants want them until at least 2052. This was the lease that prevented BAA closing the airfield in 1992. BAe are still on site albeit Spirit are the main landowners. I'm not sure of the exact ownership / lease details these days as a FOI came to nowt. The only area that would potentially go to the property developers would be the 1964 terminal should pax operations cease. With both Storm and PAM / Ryanair planning new hangars to accommodate future growth and with both these companies plus others needing the runways, the chances of the whole site being given over to property seems far fetched at this point in time. Also, the RCAF have a contract for their base until 2028 albeit contracts can be changed.