Sorry, for some reason I can no longer use the quote function.
A lot of the routes you quoted LAX_LHR are indeed either saturated and/or low yielding so what I meant was that Norwegian would not benefit from dumping capacity on routes such as TFS (which are saturated...trust me), the incumbent operators, of which there are many, wouldn't benefit and if carriers start dropping routes then the airport doesn't benefit either.
As for Easyjet (obviously you're taking my comments as being tribal) they have been operating many of the saturated routes for many years. 2005 in some cases. Plus they also launched much needed routes for MAN including ATH and SXF and thinner routes like BIO. Now if Norwegian were to do the same then that is welcome but do we need more capacity on TFS/LPA/IBZ/PMI etc ???? No. And if Norwegian were to offer these routes they may struggle. They just aren't a strong enough brand to operate such routes ex MAN (or anywhere else in Northern England) in my opinion.