I would not even call modding a success on the PC with only a handful of games that support them. It is very much a niche market.
I do hope that they can succeed but with the horrible launch on Xbox One for Fallout 4 with the mod thefts, and other negatives far out weighing any of the positives and now no mods on PS4. It might be all on Skyrim to come and sell a massive amount of copies only on the Xbox One and not that many on PS4 so the argument can be made that Mods played a factor on the sale of the game. If the sales are about the same you can then state that mods played little effect on the sales of the game and will make it less likely for the Triple A companies to support mods on the console which I doubt would happen since most do not support them on the PC.
I just hope it is successful enough on the Xbox to continue to allow Bethesda to offer mods on the console and maybe that a few of the Indies to take part as well which is much more difficult since Indies for the most part do not have enough resources to host mods and usually depend on Steamworks or third party hosting sites to host mods. Mostly it is Steamworks. Maybe Bethesda might need to get in touch with some of the Indies and see about them getting them on board and support mods on the console and maybe having Bethesda.net to host the mods for the Xbox One.