Most importantly this suggestion is only meant for if (keyword:if) N3 is made

The What:
My suggestion is that If N3 is created it should be a modded server

The Why:
Many of the features of the nations game mode are currently done through plugins, while there are mods that provide a more optimized and efficient means of providing these features, having players download a Modpack to play wouldn't be much more difficult than the server required resource pack, there is already a Modpack for optimizing N2, and there are currently (to my knowledge) no modded earth based nations servers

The How: many plugins such as Minecraft could be replaced with some highly optimized mods (i.e. Create Aeronautics/Big cannons, being able to replace Minecraft). Most of these mods are already highly configurable, and (if needed) there is even a mod to make a configurable scale earth map (terrarium continued), though a modded server would limit what game version could be used, newer features can always be added through one of the many vanilla backport mods

Again I only ask for consideration of this Idea if N3 is being seriously considered