Following "Rogue One", we now live in a world where a small thing like being dead is no bar from appearing in a prominent role in a new movie. It's fair to say that Tarkin didn't quite work, and also that it's phenomenally expensive, but those are temporary issues - we're just a few years away from the point where an actor could star in a movie without actually appearing in the flesh in that movie.
That being the case, once your upcoming "Justice League" film bombs and you're inevitably looking to reboot the whole thing (again), may I please suggest that you should start with Superman but that you shouldn't look for a new actor to portray the character?
Please note that I am not suggesting that any new film should try to be a sequel or remake of the films of the 70's and 80's. On the contrary, it very much should not - in addition to being rather dated, those films have a significant weakness in that they posit a very 'small' universe (that is, there's no room for Brainiac, or Darkseid, or similar villains, not to mention the rest of the DC universe).
But Christopher Reeve was perfectly cast, to the extent that he became the yardstick for all future iterations of the character. Nobody had embodied the role so well prior to that, and nobody since has measured up.
And while I'm at it, there are some other aspects of those films you should be looking at carefully, but in terms of the tone rather than specifics. First up, the music. Hans Zimmer's work on "Man of Steel" is fine and all, but I'm afraid John Williams just did it better. Secondly, the suit, or rather the colour palette as a whole - when doing a Superman film, your colours should be bright. If not, you're doing it wrong. (And I don't give a damn if you think those grimdark colours are more 'realistic'. There isn't a single thing about Superman that is realistic, so if that even rates as a consideration you probably want to think again.)
Oh, and finally: your focus in the character is superMAN. Depicting him as a stoic, brooding alien, or depicting him as some sort of god come down to Earth is, once again, to get it wrong. Fundamentally, Clark is a farm boy from Kansas. He just happens to be one with super powers.
Once you've re-established that vision of Superman, and once you've once again presented your new take on Batman (and that one should be dark and gritty - because different things should be different), then you can bring those together into conflict.
Or not. Some people seem to like "Man of Steel" and "Batman v Superman", so maybe "Justice League" will turn out a massive success.