Warning! Spoilers ahead for Green Lantern #4
In the latest issue of DC Comics' Green Lantern, it's teased that John Stewart may be more powerful than he realizes, perhaps even more powerful than even Superman. While the Green Lantern Corps has been nearly destroyed after a major attack on Oa, those who remain are trying to pick up the pieces, including Green Lanterns Jo Mullein and her new partner Keli Quintela. However, many Lanterns have been stranded amongst the stars after the Central Power Battery was destroyed, including John Stewart. However, a flashback to his past reveals that he may hold a secret power that he didn't know was hidden from him.
In Green Lantern #4 from Geoffrey Thorne, Marco Santucci, and Tom Raney, John Stewart has been stranded on an alien world, just like many of his fellow Lanterns. When the Central Power Battery was destroyed, nearly every Green Lantern's power ring was completely depleted of its charge. As if that wasn't bad enough, John also learns that bounties have been placed on all of the Lanterns he was leading into the DC Universe's dark sectors (regions the Guardians of the Oa couldn't see). Many Lanterns have already been killed and things have been looking pretty grim for Stewart and the Corps as a whole.
However, a flashback at the beginning of the issue seemingly teases that John Stewart may still have his inherent power as a Guardian of Oa. Back in 1990's Green Lantern: Mosaic from Gerard Jones and Cully Hamner, John Stewart was inducted as the first human member of the Guardians, ascending and being granted their great powers as critical beings in the DC Universe, perhaps becoming even stronger than Superman himself. However, Stewart gave up his role and title when Green Lantern Hal Jordan was corrupted and became the villain Parallax. That being said, it appears that though Stewart's power was merely hidden away by the Guardian named Ganthet, rather than being taken from him after he declined the position.
While Stewart's memory of Ganthet was interrupted, it seems as though John Stewart could still have his Guardian powers within himself, just waiting to be unlocked. This would be huge considering how few Lanterns there currently are, and those with power still in their rings are even rarer. Not only that, but the traditional Guardians have been taken out of the game as well. If he has untapped powers, John Stewart could actually be proactive and work in earnest to rebuild the Corps alongside Mullein and Quintela, as it's become evident that there are dark forces at work trying to ensure that the Green Lantern Corps never rises up again.
In any case, John Stewart could become the galaxy's biggest defender in the issues ahead, especially if he can find a way off the world he's been protecting and can unlock the greater power he's apparently always had as a Guardian of the Green Lanterns. Ganthet himself said that he couldn't erase his ascension, which seemingly implies that Stewart has always been extremely powerful, perhaps even stronger than the greatest Green Lantern Hal Jordan (or even Superman). He just needs to figure out how to access it so he can save his fellow Lanterns going forward.