£138M is not a lot of money and the first question is what could be achieved with it.
LBA and EMA do exist - but EMA actually doesn't do that well as a passenger airport as it is and is reliant on cargo for viability. LBA is no the best operationally but it is local catchment and log term airport airline bases which matter. LTN is arguably similar. No one suggests it should be closed.
Objectively, the DSA experiment failed I'm afraid - let it go. Don't let it raise people's hope as a political football.