EZY will always have a very different portfolio to holiday airlines such as LS/TOM/TCX. They don't have an in house holiday operator like they other three. EasyJet Holidays is just not pushed the same. Ryanair will only serve NCL similarly to EZY and that is relatively high frequency busy sun destinations. There will be nowhere exotic for either EZY or FR.
Those with established in house tour operators will try the newer routes but it will only be once a week and highly seasonal. That's not really what EZY or FR are about. Yes there are some low frequency seasonal routes however they provide year round services at a time when LS pretty much shut down. In fact on some days in winter, EZY is the only airline with any based aircraft operating ANY flights.
EZY will never be more than 3 based aircraft. The base is fairly busy and some of the aircraft we extremely high utilisation. A recent article mentioned above claims that NCL commands some higher fares. Coupled with above average onboard spend, it could very well be that NCL provides great ROCE.
They could operate AMS, OPO, LIS, VCE, NAP, HAM, TLS, LYS or they could have done FCO when it existed. The fact that they didn't suggests that the NCL base can support holiday flights but will struggle with anything city related. However if/when EZY open ACE/AGP/FAO then I do believe NCL/GLA/LPL/BFS could be at risk. They could then cover FAO/PMI/AGP/ACE/NCE/GVA/BFS/BRS/BCN from their respective bases - this could well be the plan.
If I was NCL I'd be making sure they were happy. I wouldn't want to loose the parking charges for 1095 aircraft nights per year, nor would I want to loose the car parking for all of the EZY employees as EZY actually pay for these. FR will bring pax but they won't bring me those charges? They certainly won't bring new routes that for sure - they'll just galvanised ready made markets that are already operated by the based airlines.
Also if EZY left after 12+ years it wouldn't send a great message to the airlines after flyBE also recently went, LS are practically summer only and the other two airline bring just 3 aircraft each. Would I want to open an aircraft base there given that track record? Probably not.