Heathrow will never close, with all the recent investment plus there are too many local jobs at stake if it ever did and the majority of those are unskilled and would never be able to relocate, it would cause a major headache for the local politicians and Goverment far more then building the 3rd runway.
The only REAL outcome to all this is to build the third runway that was origionally planned at Heathrow plus an upgrade to the rail link between Liverpool St Stn and Stansted Airport offering a faster service making the airport more attractive to future airline growth there.
A second runway at Gatwick would also be an advantage to the airport for lots of reasons but as your always bashing LGW I would assume you would think otherwise (Skipness)