Also the last time tv saw Tim Drake it was in 2001 or 2002 with Static Shock. Just saying.
Futhermore, audiences can't be complete idiots. They know by now Dick isn't Robin anymore. They've had three animated show's back to back to back tell them he upgraded to Nightwing.
And on all of those shows he started as Robin the first times he was seen.
Then at some point he moved on to be Nightwing (although on The Batman, that's really stretching since it was only in a Dark Knight Returns possible future episode, not really on the regular show). As I said, maybe they are looking to do that here. Maybe Barry will die, and Wally will "graduate" as well. Then Tim and Bart can come right in to fill their spots.
The show hasn't aired, it's introducing a bunch of new characters, and it's keeping 2 older ones around for at least the first season or so. I really don't see any reason to get your panties in a bunch.