I guess it is pretty much pointless to discuss it right now, as we all know LFS S2 is not the final product, and still won't be for some time. I strongly believe, that if devs will allow modding, they will do it in the best possible way for the whole community. What I understood from their previous comments, it looks like the modding tools/editors would be commercial products, with their separate support, which would be a good idea. But at this moment it is pure speculation. Anyway, with all respect to modders and their creativity, I do not care about modding of LFS that much, as majority of mods for other racing games are of low quality at least compared with the original content. All these considerations apart, is fragmenting the online play really what we need right now? What I mean by "fragmenting" is, that there will be servers running different mods, and in the end there will never be enough people playing the same "mod". But, it would all depend on how the question of modding would be solved by devs, and as I mentioned it earlier, it is too soon to even think about it.
Someone mentioned Nordschleife, and it is a recurring topic in LFS forums, which is not surprising. I can only say for myself, that I would glady pay for a "Nordschleife for LFS", if the devs would even think about buying a license.