Having recently done an enquiry for a family wishing to go skiing and fly from Newcastle, I contacted a number of tour operators for quotes.
Many of the tour operators these days apart from the big two (Thomson/First Choice and Thomas Cook/MyTravel) utilise the low cost carrier flights of Easyjet, Jet 2 etc.
This is not just happening with ski destinations either.
Its a pure fact of life that the traditional way of booking holidays as a package is a dying breed and DIY packaging (either yourself on the internet or through a travel agent) is more and more the way forward.
In summary, if you take into account the low cost routes and ALL ski tour operators not just the big 2, then all ski resorts are still available flying from Newcastle - it just may not be with the operator you want or look at.