In the recently-released solicitations for Action Comics's July 2017 issues, the Superman family comes to the Man of Steel's aid as things look grim against the powered-up Superman Revenge Squad.
The Squad, headed up by General Zod, includes Cyborg Superman (Hank Henshaw this time), The Eradicator, Blanque, Mongul, and more -- and in the final two parts of the "Revenge" storyline, they're facing off against Superman, Steel, Supergirl, and New Super-Man.
...The only people missing are Superwoman, who has her own thing going on in her own title right now, and Superboy.
One can understand why Superman wouldn't bring his son into battle against villains this powerful and dangerous -- but the presence of Mongul, The Eradicator, Steel, and the Cyborg begs the question: in this Superman Family-centric storyline, could fans get the return of the Conner Kent Superboy?
Following the Crisis on Infinite Earths, history was rewritten in such a way that Superman got his powers in his late teens and never served as Superboy during his youth. It was years before DC introduced a new Superboy, and when they did, it was during a storyline called Reign of the Supermen!, in which Superman had died and four different characters all put on a variation on his costume and claimed to either be Superman or at least to be standing in for him.
Those characters? John Henry Irons, the Man of Steel -- who would go on to become Steel, a hero in his own right, after Superman returned; Hank Henshaw, the villain known as the Cyborg Superman, who used his connections with the cosmic tyrant Mongul to rain death down upon a major American city; The Eradicator, a former Kryptonian weapon-turned-villain-turned antihero; and Superboy, later given the names Conner Kent and Kon-El, who was a clone of a human body that had been given some of Superman's powers by recreating the electromagnetic aura that made the Man of Steel invulnerable.
Despite some costume, power, backstory, and attitude changes, Conner remained Superboy for nearly 20 years, from his debut in 1993 until the Flashpoint crisis in 2011. At that point, there was a new Superboy title launched featuring a new and different Kon-El. This one ostensibly cloned from a potential, future child of Superman and Lois Lane, he had a different backstory, a different source of cloning, and different powers from those exhibited by Conner Kent.
Eventually, that version of Kon-El was lost to the timestream and has not been seen since.
Why would we assume Conner Kent, then, would be a character we might see again, as opposed to the New 52 version of Kon-El? Mostly because in the Rebirth era, there's been a tendency to embrace a "greatest hits" approach to DC history, and there's certainly a lot of love for Conner -- particularly from DC chief creative officer Geoff Johns -- and significantly less so for Kon-El II.
In a story that involves traveling to the Phantom Zone, various Kryptonians and Kryptonian-like heroes and villains, it seems like it's just begging for the return of the last major Kryptonian character we haven't seen since Rebirth. That goes double when you consider the fact that Henshaw, Irons, and The Eradicator haven't been in one place at one time except in stories that also featured Conner (and usually Doomsday, although he's indisposed at present in Mr. Oz's prison).