Ok we'll just have to disagree. It really is quite simple my friend. You have certain area of land between airports with a certain population with a certain propensity to fly. It is a finite number. Take away the deals and are the routes sustainable? Two of the most successful airlines in the world have come and gone. Yorkshire exports more passengers to its direct neighbours than anywhere else in Britain for a reason.
I repeat my earlier post:
Do you think some passengers who would have used the EI service from LBA to DUB are now using the EI service from DSA to DUB? How has this affected the LBA service - made it stronger or weaker?
If you halve the catchment you have less passengers to make services viable. Passengers = flights
A few passengers taken away from a route will end it.