They changed the lighting engine as apparently it was literally broken on consoles, it was also causing lower end PCs issues.
I doubt it will get any real mod support, certainly not to the degree of a game like Skyrim (hardly any do), remember FROM are not a PC developer and modding is really a PC only thing.
That being said I highly expect there to be some form of modding, if only in the form of textures.
you say that, but ds1 on pc became playable because of mods, it started out looking like a turd, but once you chuck on all the high res packs, up the res, it looks and runs amazing