Macdo
You rather miss the point, even if Trump were to revoke NAI Dot approval Norwegian will still continue to operate to the US under European skies through their Norwegian AOC.
With Brexit looming he is very unlikely to block NUK application, the Uk being his NBF
Ironically it is the fact that the DoT have held approval for so long that has forced Norwegian to fly to mainly the US because it works better with the restrictions than without them, otherwise Norwegian could utilise the crews in a better way for non US long haul destinations