Im going with Fate knocking over the whole Sandcastle before they get the chance. Specifically, the MC will upset the status quo by having power that breaks all the rules. Its different enough, with scary far-reaching implications, so those in power are going to try to make it/him go away, for various reasons (fear/ambition/zealotry). But more than likely Ancient Evil (not seen since the Founding of the current system) will come crashing back into the world, which will force priorities to a much more basic and darwinian vector, so that whatever works and saves the day is . Of course not everyone will be as willing or able to adapt as others, but that will be the fun part.