There are many aspects with its worldbuilding that Young Justice gets pitch-perfect. With its frequent use of time skips, the series has been able to flesh out a whole epoch in the superhero history of its world that grows organically outwards from a core cast of characters.
Now, as each season grows more ambitious, Young Justice: Phantoms promises to up the ante even further as it's set to introduce the Legion of Superheroes. Brining in the Legion will mean time travel, and if there is any superhero production that can nail that idea it's Young Justice.
The final scene of Young Justice: Outsiders gives a heavy wink to fans familiar with the comics as an otherwise unimportant waitress at a diner pours a cup of coffee while wearing a Legion Flight Ring. The ring denotes members of the Legion of Super Heroes, a peacekeeping organization from centuries in the future whose young superpowered members patrol space in the course of maintaining order. The sheer introduction of them is a natural fit for the world of Young Justice, but what they bring with them promises even more.
Since the focus of Young Justice has always been on the younger heroes that comprise the Team, an organization like the Legion only makes sense to explore. Similarly reflecting the role of adolescents and those still discovering themselves in owning up to their responsibility in the world, the two teams would have quite a lot to offer one another. Parallels like Miss Martian's psychic-entrenched character arc neatly mirror Saturn Girl's, just as Superboy's arc learning to control his anger and impulsivity matches that of Lightning Lad's. But more than nitty-gritty details, what is most ambitious about introducing the Legion is bringing time travel into the world of Young Justice.
This would be far from the first time DC had an animated series use time travel to allow its teenage heroes a glimpse into the heroes they would become or their impacts on the world. The DC Animated Universe did this with the "Future Shock" episode of Static Shock and "The Once And Future Thing" arc from Justice League, and for an even more direct comparison, the Legion was used to explore the future in Superman: The Animated Series. And while those shows handled time travel well, Young Justice has the potential to hit such a story out of the ballpark.
With its central focus on maturation and legacy, Young Justice has already covered over almost a decade of in-world time. Even from Season 1, the show felt lived in and fleshed out as the young proteges shouldered the burden their mentor's mighty reputations forced on them and it dealt directly and deftly with ambitious worldbuilding. Time travel was even already introduced through the character of Bart Allen, and spring-boarding off that concept would be an easy leap.
With its original team now fully adults in their own right and much of its latest season concerned with establishing the next generation, flinging their adventures into the future is a natural next course for the show. Sure, time travel can be a hard concept to pull off, and oftentimes, it can feel gimmicky, confusing or is so lazily executed that it mucks up the continuity of the world. But if there is any creative team that could handle such a mind-boggling task, it's the one behind Young Justice.
Young Justice: Phantoms will stream on HBO Max. The fourth season of Young Justice does not currently have a premiere date.