Just ask Toho how hard it is to create an entirely new map.
Though the problem is that creating a new campaign map is really oh very hard, lots of work and if you want it to be great and of high quality it might even take a year or so :/. We could make it like the kingdoms expansion, where it focuses only on the New Gift, Brandon's Gift, The lands of always winter, Skagos, Bear Island and perhaps some of the upper north (Glover and Umber lands) I think this kind of campaign would be great