STN are looking to attract something a bit more mainstream hence the likes of TOM, TCX, BE and SK being the sort of airlines (other than FR) that are putting new capacity into STN and not smaller start-up carriers.
MAG will be talking to airlines such as the major US and Gulf carriers, and probably some other short-haul legacies to go with SK.
STN's redevelopment project has still got a way to go and I wouldn't expect a major long-haul airline to come in before that's all completed.