Re: Robin or no Robin?
Since I imagine the next film won't be an origins movie, Dick Grayson/Tim Drake could easily be introduced in that film, even if they don't become Robin. Then have him become Robin in a sequel.
... I know - wasn't my idea."
Dylan O'Brien for Spider-Man, Jason Isaacs for Norman Osborn, Emily Blunt for Captain Marvel, Jake Gyllenhaal for Black Bolt