Blunt answer is that there isn't enough business to keep all the airports open.
Desire of eveybody is to "fly" from local airport so they don't have to drive 2 hours to nearest big one. Great so Mr and Mrs A wish local airport to have 737/320s operating out of there for the 1 or 2 occasions a year fly from there but wish to pay same price as flying from Stansted/Man etc.
Reality is that small local airports do not have a long term future but unless there is a realistic culling then they will limp on for another 15 years. Companies exiting and fresh faced business people with cash entering before they too exit with empty pockets.