Relying on Low - Costs
The original growth of the low costs in the UK was largely due to the large numbers of people commuting between mainland Britain and Ireland.
Being a foreigner in the UK myself, I know how easy it is to rely on low cost carriers to cross the channel in order to visit friends and family. Without the loco's I would probably only be able to afford 1 or 2 visits a year!!
So - if European integration continues - and more and more people start working outside their home countries, there will be an ever growing requirement for cheap, reliable air transport.