NOT saying it wouldn't be entertaining but there's no way they could do it justice at a realistic budget.Honestly, for DC, I think the answer for them is stuff like Joker.
Darker, adult content, and stand alone stories. Elseworld type of stuff.
Don't worry about copying the Marvel model. Let film makers tackle these stories and characters with complete freedom to execute whatever vision they have and see if it works. Joker worked, so why not try it again with other characters and properties?
I would LOVE a Justice League Dark film. Constantine, Deadman, Zatanna, Etrigan, Swamp Thing....all those guys in a dark and weird ass movie? I'd be down. Trying to shoehorn it into a cinematic universe though? Yeah, no thanks.