Depends entirely on implementation. Some possible outcomes:
Only large, mini-DLC style mods. Could be fine if priced accordingly. Though if this was the goal I wonder why they used Crab Armor as their showcase example.
They allow almost no mods in, making the feature essentially irrelevant. Contracting individual modders for larger projects is something they could do right now if they wanted to, but they aren't. And if they allow a few smaller projects in, then why go for the one paid armor mod when there are fifty free ones of equal quality.
They let everything in, making it a steam greenlight-like shitshow. By far the worst option for the community. The list will be filled with low-effort crap. Free modders will start thinking "why are THOSE guys getting paid when my stuff is just as good." The overjustification effect kicks in and people start losing interest in doing free mods at all. The remaining free mod market will be filled with either direct piracy or cheap knock-offs of paid mods, and Bethesda will be forced to do copyright takedowns on their own community, ending in everyone going toxic and leaving.