Truth of the matter is that if Van Air disappears from the island, so will 50 per cent of the airport's destinations - all that will remain is DUB, LCY, LGW, BRS, LPL, BHX and MAN. And realistically, destinations like LCY, BRS and BHX do not look like a given. The airprt could very well be down to a core network of LGW, MAN, LPL and DUB some point in the future.
I think it is fanciful to believe that another airline will simply show up and continue the routes Van Air has flown at the fares they have offered. While 10 or 15 years ago there were dozens of airlines with small commuter aircraft around, this nowadays is an almost extinct species. While almost anywhere else it means driving for quite a distance to catch a flight with the big boys from a big airport, in the case of IoM it means, well, swimming, I suppose.