You know, on second thought, Nightwing in a Titans movie might help the franchise. If they bring in an older Nightwing and the movie goes over well, it might make people want to see Robin in a Batman movie more. They'll see him as a cool, darker character, and it'll shake up some misconceptions about the kid.
Also, they could show just a quick glimpse of his Robin costume (showing people it doens't have to have little yellow booties), so people dont freak out about that. Could be a good idea.
Besides, this could be the first step in setting up an interconnected DC Film Universe, which I really want. This is one advantage DC films could have over Marvel (besides their quality), and they should use it.