Warning: SPOILERS for The Flash #48
The one true Flash, whoever that may be, is coming to the world DC Comics. Currently, DC Comics' solo The Flash series is in the middle of a storyline called "Flash War," which pits several Scarlet Speedsters against each other. The main conflict has been between Wally West, the original version, and his uncle, Barry Allen.
The flashpoint, pun very intended, for the battle is the return of Hunter Zolomon A.K.A. Zoom. It's through Hunter that Wally has finally remembered that he used have children with his wife, Linda Park. As of the latest issue, The Flash #48, Hunter has told Wally how to get his children back but that's only a small part of Hunter's plan. Zoom's grand scheme involves the return of the true Flash for unknown, probably, nefarious reasons.
Though the hints of how "Flash War" would occur have been littered throughout The Flash's series lately, the war really starts in The Flash #48. Wally and Barry both want to find a way to bring Wally's kids back but Hunter Zolomon is the man standing between them. Zoom is feeding the younger Flash's worst and most foolhardy impulses. Although Hunter has just appeared since the reboot of the New 52, The Flash #48 jumps right back into Wally's complicated relationship with Hunter.
Before Hunter Zolomon became Zoom and tried to ruin Wally's life to make him a "better her," he was Wally's friend. Hunter uses that relationship in The Flash #48 to convince Wally that the only way to save his children is to break the Speed Force. According to Hunter, like Wally, his children are trapped in the Speed Force. The only way to get them out is break the mystical force that binds all speedsters down. Barry, obviously disapproves of this huge and potentially universe changing move. Wally though believes he's in the right and Hunter isn't lying about the damage he'll cause. Wally is, of course, wrong.
When Wally runs off to break the Speed Force, with Barry behind him, Hunter is left behind. It's revealed that Zoom wants to release someone else from the Speed Force. Hunter is left alone with Commander Cold, as well as Iris West and Wally West II (who is now just being called Wallace). With the trio, the calm facade of Hunter has portrayed with Wally breaks and he shows his true fanatic colors. Hunters expresses a desperate hope that Wally and Barry are finally on the path to "the true Flash."
Anything more about the true Flash isn't revealed. Despite Commander Cold's best efforts, Hunter Zolomon escapes and does something to change the timeline in the process. Yet there's plenty to speculate about who the true Flash could become, even it doesn't make a whole lot of sense why Hunter would want him out of the Speed Force.
DC's mini-event The Button, where The Flash and Batman teamed up against the Reverse-Flash, ended with the return of a classic character. At the very end of The Flash #22, the Golden Age Flash Jay Garrick appears out of the Speed Force, just like Wally in DC Rebirth. Jay tries to convince Barry of his identity but Barry doesn't remember and Jay disappears. Jay hasn't been heard from since and is presumably still trapped in the Speed Force.
As Jay predates nearly every other speedster in DC Comics canon, he would definitely qualify as "the true Flash."
The only confusing thing is why Hunter Zolomon would be excited about Jay's return. The characters had no relationship together pre-Flashpoint and what interaction they did have was very antagonistic. Unless, of course, Hunter thinks he can use Jay's fragile state after being broken from the Speed Force to manipulate him and do something dangerous, maybe even bring back his own speed. Otherwise there's no obvious reason for Hunter to want Jay around.
However, it's very possible that Flash War won't just be a battle between Wally and Barry but everyone that has ever held The Flash title, including Jay Garrick.
The Flash #48 is available now from DC Comics.