Warning! Spoilers ahead for Infinite Frontier #6!
In Infinite Frontier #6, DC Comics just confirmed how Darkseid's ultimate form works. The former ruler of Apokolips was reborn before the events of Infinite Frontier #0 where he was teased to be DC's next big crisis-level threat. As he returned, Darkseid claimed that he was rebuilt from his lesser forms and crafted into his true, ultimate form.
Throughout the Infinite Frontier miniseries, Darkseid has been working away in the background as he enacts his plans for the multiverse. One of his key helpers was Psycho-Pirate who helped him recruit the Flash, against his will, by using his manipulative powers. Psycho-Pirate did everything right up until this issue's closing moments as suddenly phased out of existence, teasing another crisis event where he will be needed. Likewise, Darkseid also teased the next stages in his master plan that will continue beyond 2021 and into next year.
In Infinite Frontier #6 by Joshua Williamson, Xermanico, Romolu Farjardo Jr., Darkseid says, “All my pasts' versions combined into one ultimate version.” The former ruler of Apokolips' comments, along with other current versions of Darkseid, make it clear that this version of Darkseid isn't the only one existing in DC Comics right now. Justice League: Last Ride takes place in a version of the future after the team defeats Darkseid. Because of its future setting, it wasn’t clear: did they beat the Darkseid's ultimate self, or is this an Elseworld? From what readers have been told, it seems that Justice League: Last Ride is set in an alternate reality with their own Darkseid. Likewise, in Justice League Infinity #3, another iteration of Darkseid is seen who is not the same character.
Therefore, it can be assumed that other realities still have their versions of Darkseid and that Infinite Frontier's isn't the only relevant Darkseid left. Although the "one true Darkseid" doesn't confirm any of this, his wording, in Infinite Frontier #6, implies that all of his past selves have combined into one, ultimate being. In the end, the greater Omniverse didn't lose its other versions of Darkseid, it just so happened to create an ultimate-form Darkseid to add into the mix.
It's unlikely that the proceeding events in Infinite Frontier will explain the little details about this Darkseid's existence since it's already done some heavy implying which is more than enough for readers to gain their own ideas and understanding. As seen by the issue's ending, Darkseid isn't going anywhere as he takes his next steps to conquer DC's Omniverse. Infinite Frontier #6 is available now in comic book stores and on digital platforms.