Look at DOOM 2016 after the first hours of mp beta there was a guy who was able to extract content, modifying and spawned AI enemies into the dev/test room.
Halo Wars was most anticipated game for PC and with the release of Definitive Edition and the statement about no mod tool plans, a guy created an tool to extract and reintegrating of files. They never need an announcement for mod tools or similiar. An game will be pirated due of his fame. Is it an anticipated AAA game and so on…
Another example, Star Wars Battlefront 2015, it got an offline Skirmish mode with bots
and it was a very anticipated title but today not anymore! The scene isn’t interested because the world wasn’t anymore interested before the offline mode was released. And it has Denuvo! Blessing in disguise!
And getting mods for an workshop safety game… isn’t an problem at all.
Same with DLC’s for steam 
Here another fear since Dying Light and The Witcher 3…
i don’t need cuted and missing tools, e.g. Level Editor 
How about modding tools instead of Act III ? Maps can be extended as well as story added, only things that are hard to do is to create new game mechanics.