According to MOL, there will only be one, maybe two, low-cost operators still in business in the long-term. This was a statement made a few years ago.
Southwest, WestJet, JetBlue, Spirit, AirTran, Allegiant, SunCountry, 1Time, Mango, Air Asia X, Transavia, Vueling, AirBerlin, Germanwings, Wizz Air, Jet 2, Flybe, Virgin Blue, JetStar all probably have a view on the accuracy of MOL's gems of wisdom. Admittedly a lot of other airlines have gone, but there are plenty more out there other than this list, operating or about to take the plunge.
When MOL said this, I am pretty sure he was referring to within Europe. Not worldwide.