Related to that, what would you want the DCU to do with DC characters and stories? For me, that would be the following:
Storylines about mythology and the gods: Mostly about the Olympians since they're easily the deities with the strongest focus thanks to Wonder Woman. And by storyline, I mean actual storyline. Not the American Gods-like deal with "gods need worship to stay relevant, now they're secondary at best" or what the DCEU did with them having been slaughtered or relegated to the background (even though I really like Ares from the first movie). I want Zeus, Ares, Poseidon, Athena and co to have actual presence in the story. I want literal gods still dressed in Ancient Greece fashion messing with humans for various reasons, I want Ares to plot wars, etc. And I want them to be powerful, like at the top of their power. I want it to be near-impossible to directly fight them, I want displays of power worthy of mythology. It would also be really cool if gods from other pantheons would show up, like the Norse Gods. Odin in particular. I want mythological stuff in general to appear.
Supernatural focused stuff: I'm really into fantasy elements and I love the occult side of DC. We know Swamp Thing will have his live-action story so this gives us hope but I really want more of the magical side of DC to be put to live-action. I want Constantine (though topping Matt Ryan will be damn near impossible, Ryan IS Constantine, he is to John what Downey Jr is to Iron Man and Hugh Jackman to Wolverine), Zatanna, Dr Fate, Madame Xanadu, Morgaine Le Fay, Merlin. Fate in particular I feel could get an awesome storyline with his inner conflict related to Nabu and the Lords of Order. I would also love the Justice League Dark to be in the DCU.
More esoterical & primordial side of DC: I would love if Gunn decided to tackle the more greater-scale aspects of DC. You know, the Source, the Monitor Overvoid, Lucifer Morningstar. It would be interesting to see how they deal with Heaven, Hell, etc. Not necessarily too much focus, just one or two flicks or series and then they make cameos, appearences or references. Like, imagine a comic-book accurate Lucifer, with style, power, sociopathic behavior and all. Similary, I would love Hellblazer to get a focus. I want something like City of Demons, with Constantine and notable characters from Hellblazer and the more disturbing side of DC, like Nergal, the First of the Fallen, Chas Chandler, Nightmare Nurse, Papa Midnight, etc. Imagine the variety of characters and interactions.
More comic-book accurate Batman stuff: I love Nolan's take, I love Battinson but I'm getting tired of Batman being only seen through the realistic lens. Creature Commandos already showed him interacting with the weird, full comic book world so we know he will be more "fantastical" but I want more. Brave and the Bold will have Bats meet Damian so the League of Assassins will probably appear and if they do, I want them to embrace the weird stuff. I want Ra's al Ghul to be the 600 years old genocidal conqueror who baths in a fountain of youth that can rejuvenate him and even resurrect the dead like in the comics, I want Poison Ivy to actually control plants, I want Solomon Grundy to be an actual zombie. And above all, I want the Joker from the comics. I love Ledger's take but I'm tired of so many versions always imitating this. I want a more comic-book accurate Joker, like in TAS or the Arkham games.
Variations of enemies for big movies: Should the DCU go the MCU way with a few big reunion films, I want each film of these great reunions to be different in tone and scale and have different enemies. We will already get Brainiac and if Darkseid appears, he should be the great big bad but there are plenty of other enemies in DC that can serve as great villains for a major film. Mongul, Despero, the Red Lanterns, the White Martians, Eclipso, Prometheus. Heck, we could have the Legion of Doom with previously established villains, like Lex, the Joker, Gorilla Grodd, Sinestro, etc.
Introduce not often used characters: This one I have good hope for, Gun has a taste for using obscure characters. I want the DCU to show people like Static Shock, Onomathopeia, Black Alice, Yuga Khan, Detective Chimpanzee. You know, weird characters few people know about.
Darkseid's powerset: Minor one but I wish adaptations would remember Darkseid has other things in his arsenal than the Omega Beams. Most versions just show him using the beams and his super strength and speed, with the other power he uses being at most being flying. In the comics, he can control energy, has telekinesis, transmutation, necromancy, can trap souls, etc. I want an adaptation that goes with that.