Yep.
A friend of mine likened this to "the magician's choice", the old card trick where the illusionist asks you to pick a card without telling you what he is going to do with that card once chosen... it appears you have a choice, but everything is truly determined.
Let's say a campaign relies upon the rise of a necromancer to power to hatch his sinister plot. The players kill him. All the sudden, the necromancer was merely a lackey, and it's his former apprentice rising to power that the PCs must contend with...