WARNING: The following contains spoilers for the first 12 episodes of Young Justice: Phantoms, streaming now on HBO Max.
In Young Justice, fans have seen the Justice League really struggle with evil forces on Earth, as well as off-planet. The Reach, Darkseid's troops, the recent Martian war and Klarion's meddling have all taken tolls on the seniors, which is why they were keen to green-light projects like the Outsiders, so they'd have youngsters ready in case ranks got thin. Now, come Young Justice: Phantoms, the series' latest crisis has left Superman's team short once again, leading to another major shift in operations.
It occurred as the League took stock of the damage done by Child, the Lord of Chaos who has the combined power of all the others. She broke Klarion the Witch Boy in the blink of an eye, then schooled Doctor Fate and Team Zatanna, before teleporting all over the globe to cause mass destruction.
Some places have been turned to volcanic pits, with hurricanes and snowstorms happening elsewhere. Even villains like the Wizard had to help out, as everyone had to act in the interest of self-preservation. And this hour of desperation is addressed in the finale as the credits roll, with the Man of Steel planning with Black Lightning and Nightwing in India.
He couldn't believe they were so depleted and that no one has tracked the Child down, telling Jefferson they needed a new plan for crises like this. To him, the Phantom Stranger's vision of building a network to fight the Child made sense, which is why he wants a Justice League Reserves system. Sure, Young Justice and the Outsiders help out, but they're still cutting their teeth so more experienced folks are needed, especially because he can't trust villains all the time, which opens the world of possibilities.
That said, maybe Kal-El, Batman and Co. might offer amnesty to villains. They'll have to keep a close eye, but one can see redeemed criminals like Cheshire and the League of Shadows coming in because they all want to save the planet after the sick wars waged by Vandal Savage and the Light. It'll be an intriguing mix, fraught with tension and conflict, but these alliances would make for great stories.
In addition, the Outsiders and Young Justice rosters could now be pushed even harder in training and on junior missions to garner promotions. Nightwing and Artemis can lead this initiative with Aqualad, just like they've done this in the past. However, with Cassie/Wonder Girl, El Dorado and the rest already chiding Beast Boy for weakening their roster already, this competitiveness might find some losing sight of the cause.
Regardless, this is a natural direction and evolution of the Watchtower's entire superhero initiative, albeit expedited because the seniors are tired. Thus, all that remains to be seen is who's ready to step up and who won't be able to handle the challenge.
See how Superman and the Justice League get stretched thin in Young Justice: Phantoms, streaming now on HBO Max.