It is understandable that everyone is comparing Dishonored to Blades in the Dark. Personally, I am not big fan of the second one – i agree that this game is quite innovatory, faction system is impressive, but after all I don’t really like inflexible scheme of session and setting - maybe it is similar to the Empire of Isles but fantasy elements in Blades are much more common. For me, Dishonored has grim, industrial universe where magic is kind of addition, and I really like it. So I am glad that there are two, similar but on the other hand different systems.
Dishonored is very flexible – in rulebook we have detailed description of two cites and two others, just outlined Islands - Morley and Tyvia - which you can use for more openworld campains. I can think of a few conventions that fit the game:
game in the convention of politics and intrigue, with rivalry between aristocrates, parliament and emperor, plots and treasons. Mayby even more „heroic” campain where players decide about fate of the entire empire – for example dreadful plot that would lead to next Morley Insurection and disintegration of the empire.
fight for survival in the streets of Dunwall, perfect for faction wars (here elements of Blades in the Dark will be very usefull) where players control one of the gangs. Or mayby game in criminal convention where main goal is to solve a case of mysterious murder, with collecting evidence and hearing witnesses.
convention of mysteries with horror elements – cult of the Outsider, cruel Abbey of the Everyman, incomprehensible Void and adventures in dark atmosphere from H.P. Lovecraft’s book.
and finalny, adventure convention – you can take yours players to the Pandyssia Continent where you can put literally anything you want, send them on the epic whale hunt or on fighting with pirates on the high seas.
I think Dishonored system gives many, quite varied possibilites. It is always good idea to ask your players what type of adventures they are expect. Of course this is all my opinion and is mostly theory becouse I haven’t played yet, just preparing upcoming campaign.