It's true - Thai to stop flights to Udon in April

http://www.bangkokpost.com/news/local/29940/thai-flight-halt-riles-udon-trade-chamber

Even if Nok add three flights to replace them it's not a lot of ucse as most time I fly south I am getting an international flight, and Nok flies to Don Muang.  So that leaves a twice daily Air Asia flight, which as a result will be full and I would guess average fares will be higher.

As for them closing the flights because they are making losses, almost everytime I've flown the flight has been well above 90% full.  I guess it's more about getting a return on their investment in Nok