well here insider news its confirmed that man of steel is the first movie to start collecting DC character for Justice League, but Christian Bales batman is not part of it
and yes this was the last Iron movie that RDJ will do, not including cameos in Marvel films, and Avengers 2, think of what Hugh Jackman did with Xmen, all of them were contracted for 3 films but then Hugh went on to do spin offs, such as Origin:wolverine, First Class, and Wolverine