After a recent question asking if the Xbox One will support mods, Major Nelson responded it's up to the developers. I'm surprised they're giving thought about implementing mod compatibility, that would be very impressive if they decided to allow it. All we can do is wish and wait.
Via Nowgamer"It's up to developers to support that," answered Microsoft's Major Nelson. "These are two very different things."
His answer suggests that the capacity for modding is there, if developers create games in a way that will support it.