Nowadays pure stealth is like a dirty word. It's simply not seen as mainstream enough to justify the development costs, thus stealth is virtually always treated as an option. The typical company line is: "You can go in guns blazing or take a stealthy approach!"
The shift is very obvious in series such as Splinter Cell and Metal Gear Solid, with more and more concessions made to amp up the action. But that shift comes at a cost.
Part of the reason Thief was so successful was precisely because you couldn't go in guns blazing. Yes, you could exploit the AI's poor pathfinding to win battles, but the game was clearly designed to punish un-stealthy players. You were meant to always feel vulnerable.
The dilemma is: Once "guns blazing" becomes an equally viable option to stealth, how do you maintain that sense of vulnerability? Doesn't the world necessarily have to become less threatening to allow for that type of player empowerment?
This, I think, would be the main challenge in crafting a game like Dishonored. Can you strike a balance that keeps the stealth just as tense and satisfying as in a dedicated stealth game like Thief, or must there be a compromise that will result in a "good, but not great" overall gameplay experience due to trying to please everyone?