It was a fact that Ledger was signed on for 2 films.
Also a fact that Nolan never had any intention of using Selina Kyle until his brother Jonah brought it up.
Therefore we probably would have ended up with quite a different third film.
(and even if he wasn't signed on for 2, they would have brought him back - it's business, WB saw what Joker/Ledger did for that franchise. It would have been silly of them not to bring him back)
--dk7
Just thinking of hardy and ledger in a scene together as these characters is mind blowing.