At the moment, the only thing players know about Fallout 4 modding is that it will be possible, Bethesda will be using Bethesda.net instead of Steam Workshop, and PC mods will be transferable to the Xbox One and PlayStation 4 version.
Otherwise, the developer is too busy with the game launch to reveal other details, as evidenced in this exchange with PR manager Pete Hines:
@Sepherchorde If it's ok with you, we're gonna focus on the game release first and talk about mods when we've figured some stuff out.
— Pete Hines (@DCDeacon) October 26, 2015
So, for gaming sites who are eager to know if they’ll be able to host Fallout 4 mods, there won’t be any answers until at least after 10 November 2015 when the game is finally available.