We had the same crazy debate on the Thomas Cook thread some weeks ago (from the same poster, IIRC) that the solution to long-haul viability problems is to move services to Stansted. I agree with the poster earlier who suggested Primera's popularity was due to being so ****ing cheap. Thomas Cook clearly hasn't found long-haul at STN to be the proverbial pot of gold at the end of the rainbow as they have pulled it completely. Quite why anyone thinks Norwegian at STN would be any better (or less bad) than Norwegian at LGW or anywhere else is deluded. The competitive situation will not change and the legacy carriers will maintain cheap fares from London to Austin, Fort Lauderdale, Tampa, Seattle, Denver etc from whichever airport they fly, so Norwegian's yields and loads will be constrained by overall demand and market pricing set by others.
Put another way, Norwegian is the only carrier on Austin, Denver, Chicago, LAX, Seattle (and probably others) at Gatwick. The data published on-line recently by one of these analysis companies showed all of those routes were losing money (if the data is correct). With the size and scale of the Gatwick catchment plus the level of onward feed available with easyJet and Norwegian's own network, those routes aren't working. It debunks the concept that a route with no competition at that airport will do well enough to be sustainable. On that basis, with limited feed and a catchment area which certainly isn't any bigger than Gatwick's, Stansted will probably do worse.
Can we park this lunacy of moving all failing services to Stansted where the streets are paved with gold? Yes, Emirates have (by the looks of it) found something that works at STN and best of fortunes to them. However, they also make several other things work - e.g. routes from Newcastle and Birmingham to Dubai - where neither can sustain hub-aligned services to New York, even seasonally. It's great that they do. But it is an outlier in the long-haul market and their apparent success at STN is no sign that other long-haul ventures can work, just as they haven't at Newcastle or Birmingham.