Maybe we will see the opening of a new airline that operates smaller props. There seems to be a complete lack of this in England. Some say there are not the markets for it but lets say someone started up at Luton with regional props heading to the likes of Waterford, Guernsey, Isle of Man, Jersey & even Newquay. Surely you could fill a J41 and make it work. Eh who knows.
Also Luton isnt as space constrained as some make out, Yes there would be problems if you wanted to build an extra 3 runways and 100 stands but there is certainly places to expand on the current site. The problem is as we have all mentioned before it is a hugely unorganized mess. Car parks in the wrong place that could be much smaller, Multi storey and tucked off out of the way.
Might I also add, A huge lack of flights at certain times. Whats the point in building tonnes of new stands if the airport doesnt attract any new services? Look at the schedules, Yes it is winter but some days there are over 2 hours between airline flights. Luton is not as full as some people think, It is a "London" airport.. those slots should be filled up.