Daniel Radcliffe sat down with Buzzfeed Brews for an interview. During which he was asked if he would ever do another mega franchise which he replied of course. He then was asked which one so he answered that he wants to be Robin to Ben Affleck's Batman in the upcoming reboot that's rumored for 2019:
Last we heard was that Nightwing (The first Robin) might be making an appearance in the then titled Batman vs Superman film. But this was all before Chris Terrio took over the script duties in December and the character might have since been cut from the script. So The Batman might end up with the first live-action Robin since the 1990s when it was Chris O'Donnell
If they ever did add a Robin/Nightwing into the new Batman films I always loved the idea of no one knowing Dick Grayson's identity like in Young Justice. He constantly wore sunglasses and was only called Rob by his friends. He was forbidden to tell anyone his identity by Batman.
Of course Radcliffe could be another Robin like Tim Drake and doesn't necessarily need to be Dick Grayson...
The Batman is rumored to hit in 2019