But, in Star Trek, the best way to solve any problem with the Enterprise is to reverse the linearity.
I'm curious about some thing though. The Shaman, you talk about NPC's in your world having pre-scripted fates. If the PC's do not intervene, NPC X will die on a certain day in a certain way.
How is that not a pre-scripted event? I thought that in a sandbox, nothing was pre-scripted. Now, since there is no way the players could possibly know that NPC X is going to die on a particular day in a particular way (unless they read your notes), does it actually matter?
To put it another way, what makes it better that NPC X will die on such and such a day in such and such a way, predetermined before play even begins, vs a DM who decides that NPC X will die in such and such a way in order to serve a particular theme or plot development in his game?
Since the event is entirely pre-scripted, and, since the PC's have no way of knowing that he's going to blow his own brains out on such and such a day, they have no way of actually preventing this, how is this not a railroad? It's an event which may affect them (if they have ties in some way to this NPC - if they don't then who cares if he lives or dies anyway) that they have zero control over not no ability to affect.
In what way is this not a railroad?