Warning: Very minor spoilers follow for The LEGO Movie 2: The Second Part**.**
Audiences might not have been as in love with The LEGO Movie 2: The Second Part as some expected, but if there's one thing that seems to be universally loved about these films, it's Batman (Will Arnett). Once again the toy-sized Caped Crusader was a scene-stealer, his narcissism and shredded abs earning big laughs. But he wasn't the only superhero in the movie and the sequel seemed to love including other DC heroes. With The LEGO Batman Movie 2 in development, it makes total sense to expand the LEGO DC-verse and go all-in on a LEGO Justice League movie.
One of the great things about the LEGO movies is that they have access to a huge repertoire of characters across pop culture, many of which belong to Warner Bros. That means in one LEGO movie, you can see Abraham Lincoln, Gandolf, Teenage Mutant Ninja Turtles, and Ruth Bader Ginsburg all pop up in one scene.
That's already awesome, but Warner Bros. also allows seemingly every DC comics hero and villain to appear in these movies, too. Batman is obviously a big character, and Superman, Wonder Woman, Green Lantern, and others have gotten some quick screentime during the main LEGO movies. The makers of these movies seem to have a ton of fun including DC characters and having some laughs at the expense of Warner's DC films.
Case in point, early in The LEGO Movie 2, the Justice League is called upon to go on a mission in space to stop the Duplo aliens from invading. It's telling enough that writers Phil Lord and Chris Miller chose the Justice League and not a random assortment of Master Builders, which arguably would have been geekier. No, they chose the Justice League and not just any Justice League -- the DCEU version.
This Justice League has Superman, Wonder Woman, Flash, Cyborg, and a Jason Momoa Aquaman who shouts "My Man!" straight to the camera (it's awesome). That's a very specific version of the team and it doesn't stop there. Lex Luthor and Green Lantern make an appearance, not to mention three different versions of Wonder Woman.
On top of that, there is a whole song in the sequel dedicated to dating Batman (which also includes Superman) when he's not even the main character!
DC characters seem to be clear favorites of the LEGO movies, and it seems only natural to go 100% in and use The LEGO Batman Movie 2 as a vehicle for a Justice League movie.
The LEGO Batman Movie obviously focused on Batman and it kept things firmly in Gotham City, packing its cast with familiar faces like Alfred, Robin, and Jim Gordon, in addition to every single Batman villain ever. The movie went hard on Batman, creating a fun look at a timeless character while being unafraid to make fun of everything about him.
So, where do you go from there? They've already tapped every Batman villain to the point where other franchises needed to loan their bad guys to raise the stakes. The answer could be to go beyond Batman and open the door to the entire DC Universe.
There's actually some precedence for this. The LEGO Batman video games did exactly what I am pitching. The first game was all about Batman and his world, and then in the sequel, other DC characters became playable. Then the third game was basically LEGO Justice League, but was still named after Batman. It worked! Those games were fun and there's only so much you can do with Batman when you've got access to so much else.
The LEGO Batman movies should follow in this example. Will Arnett's Batman can still be the lead character (though, you could argue LEGO Batman's shtick works a lot better in smaller doses), but upgrading the Justice League from cameos only helps to strengthen the sequel and make it a must-watch for fans.
For one thing, a LEGO Justice League movie would already have some of the core cast in place. In addition to Arnett, Channing Tatum does the voice for Superman while Jonah Hill and Cobie Smulders voice Green Lantern and Wonder Woman, respectively. There's a chance that the roles could be recast for whatever reason, but that's already some great talent right there. The best situation would be if all those actors stayed on.
Side note: Jason Momoa is credited for voicing Aquaman in The LEGO Movie 2. It would be really cool if he voiced a parody of his own version of Aquaman in a LEGO Justice League movie.
One of the things that The LEGO Batman Movie excels at is poking fun at its source material and superhero films in general. The film has a lot of fun with Batman's long history in pop culture and there's plenty more material to mine from DC. I'd love to see what a sequel has to say about the DC Universe in general. Not to upset those who are fans of Justice League, but it's not like there isn't enough to make fun of.
One final note to consider is that an animated film -- even one built with LEGO bricks -- has no limitations as far as what can be seen on screen. It can go as nuts with the action as it wants without feeling the restrain a live action film would. Additionally, any number of characters could appear in the movie as it runs through the DC gauntlet. Those characters don't even necessarily have to be DC ones either. The LEGO Batman Movie had Batman fight Voldemort so anything is on the table as far as I am concerned.
A LEGO Justice League movie has the potential to be a lot of fun, and it's a natural step forward after taking a Batman-centric focus. I love the LEGO franchises take on Batman and that's why I want to see what it would do with other DC heroes and villains. There's plenty more love to go around and LEGO clearly enjoys working with these characters and having a good time with them.