I think it would be really impressive if they kept Diggle as Green Arrow permanently, really committed to a lasting change. That's something that comics used to do back in the '70s-'80s or so, before the influx of a new generation of writers and editors who were driven by nostalgia for the comics they grew up with and started resetting everything over and over again.
I could see that happening if Stephen Amell's movie career took off and he wanted out of the show -- sort of like what happened with his cousin Robbie as Ronnie Raymond -- but my preference would be for Ollie to move permanently into a civilian supervisory role.
I could see that happening if Stephen Amell's movie career took off and he wanted out of the show -- sort of like what happened with his cousin Robbie as Ronnie Raymond -- but my preference would be for Ollie to move permanently into a civilian supervisory role.