Problem with trying to do the Secret Wars as a movie is all the intros. You can’t really make a movie that’s just for people who remember the original comic series, so all those heroes and villains (over 50 in all as I remember) would have to be introduced, that could take well over half the movie. Either that or they’d have to chop out most of the characters. While Secret Wars was a great set of comics (we’ll ignore Secret Wars II cause that sucked) I just don’t think it’s filmable.
It would have to be at minimum, a trilogy. A good chunk of the heroes were well known, but I agree the villains would need more intro.