There is the possibility Azrael escapes and realizes his dream of becoming the next Batman, even if Bruce himself was against it. Although Azrael due to player decisions may have been imprisoned following the events of the game. Knightfall is also a comic arc where in Azrael took up the Batman mantle to fight crime when Bruce couldn't for a time, it should also be noted that this arc was also heavily influenced by Scarecrow.
However Dick Grayon could easily trade in his life as Nightwing to become Batman, as he has donned the suit in the comics before.
This includes defeating all of the Arkham Knight's militia - the Road Blocks, Watchtowers, Mines, and of course, the last leader of the militia - Deathstroke. The Complete Knightfall Protocol can be enacted only when Batman was apprehended ALL of Gotham's Most Wanted.