Wow, just like that ending to the JSA: Thy Kingdom Come. It also remind me of a movie I saw on Plex years ago. Basically about a group of kids who get in a time machine belonging to an old me, screwed it up, went back to fix it while picking up a copy of that kid, who disappeared, joined a ZoneCop thing, and turned out to be the old man who owned the time machine. Can't remember the title for the life of me.