This might be something for future purposes. But right now, what exactly will you "do" in this offline mode except exploring the big, empty and quiet multiplayer maps?
If you count away the Online mode with all the players talking and roleplaying.
Everything else you can do inside the game today you can do just fine from the map maker, object maker etc.
If there was hunting, collecting items and things like in IT, then this would serve a purpose. But right now it would be no use.
Another thing to keep in mind is also that all your characters are saved on the FH server. So in this offline mode you would just have a presetless character to run around with as it seems.