Aquaman is slated to be in a JLA movie, that is probably where he will shine and where he will remain, especially now that the Namor movie is coming out before Aquaman (Namor was created first so its fitting.)
I can see Aquaman being in the movie like Martian Manhunter is in the comic, or the way Hank Pym is in the Avengers comic, where he wont be seen outside of the team because he doesn't really draw interest outside of the team. I see Aquaman being like that in the movies, at leat until the JLA movie comes out and then he can get a solo film.
As for Firestorm, I would love to see it. It would be very very very VERY different.
(a scientist and a jock get merged together because of a lab accident and become ONE hero named Firestorm, who has the power to turn one element into another and allowing him to turn bullets into flowers. But he still has two minds.)
That is SO different. But I am affraid that might be just TOO different for non-Firestorm fans.
It might turn out like the Ghost Rider movie.