Darkseid would be a great way to make a dark and somber JL film. Darkness taking over, evil spreading, blah blah blah. They have so much to work with.
Btw I find it funny that DC is wanting to go dark compared to Marvel which I think has struck a pretty good balance. While this is exactly what distinguished Marvel's comics from DC's for most of their history









How exactly does one go about grounding the JLA in reality given their extraordinary powers? I cannot see that working. We don't need the JLA if they aren't battling Darkseid et al.