Don't know about the Airbus family but on all the Boeings I've ever flown, a certain amount of pilot input is required before the aircraft can actually land 'automatically'. To the uninitiated, the most important of these actions include:
1. Setting the Autobrake
2. Arming the LOC and GS
3. Lowering the landing gear
4. Making the appropriate flap selections.
Now, assuming that they do invent this 'override' function and can reprogram the FMC and direct the a/c to a new destination, I would think that the modifications required to permit the controlling of the above numbered items alone would make the cost of potentially saving a few thousand human lives prohibitive. To use the automatic functions as they are today, and assuming full CATIIIB (rules out B737's) availability at the destination airport would still require so much investment that I would hazard a bet that the powers that be will find it cheaper to scramble a few fighters armed with air to air 'autoland' missiles!
Why not just design some ejecting passenger pods? I seem to recall one person posting here many years ago actually trying to patent his own design. I think the Chemtrailers finally got to him though!
Breath holding not advised!