Take this with a grain of salt, or even less, because I have. A friend of mine has told me that another one of his friends is supposedly auditioning for the role of Robin in Batman 3.
Here are the rumors about Robin:
1.) Batman 3 will take place 15 years after TDK.
2.) Dick Grayson will be wearing his costume as "Robin" while he performs as part of a circus group. This costume will be very close to the costume in the comics.
3.) Dick Grayson runs away from the circus after he is threatened by his boss and survives on the streets of Gotham by stealing. Bruce takes him in after seeing his potential, and seeing how much like Bruce, Dick is. This is where Robin receives his new costume, which is more akin to how Batman's costume is.
REMEMBER: Take this with a very BIG grain of salt! I highly doubt this is true, but you never know.