The Future Man of the Future

He's "so different" from the original Superman of Krypton?  He's got a slightly different appearance, but he still has all of Superman's powers, wears the same uniform, does the same kind of superheroic feats, and still works as a reporter.  Yeah, they give him a futuristic sounding name, and his weakness is not to Kryptonite, but to ordinary seawater.

The story begins with Superman being made a lawman for the Federation of Planets.

Now there are some obvious problems with that statement.  First since this story was set 1000 years in the future (when it was published), that implies something like 40-50 generations later.  Presumably our Superman would have many descendants, not just one.  And some of them would no doubt be Superwomen, not Supermen.

This Superman's first task is to stop a rogue planet from destroying the solar system.  Of course, this is just a slight variation on our Superman's continuing battle save the world from asteroids and meteors.  This Superman also has his Fortress of Solitude, although his is so different; it's located out in space.  Some crooks try to get into it to steal some weapons, but Superman catches them.  We get more of the creepy DC scientofascism here:

Doesn't that "click...whirr" inspire confidence in the infallible nature of the computer?  What's the slowdown, you ask?  Well, they have a ray that slows people down to about 1/10th the speed of normal humans, which renders them harmless.  And also defenseless.

The story ends somewhat abruptly with Klar getting an assignment from his robot editor.  Muto, the future Superman's greatest enemy, has been spotted robbing a Neptunian bank.  Klar realizes he must track the alien down.

The tale of the future Superman continued about six months later in Action #338-339.  Muto reveals to three of his henchmen why he wants to kill Superman.  See, his parents were on a trip in space when Superman (actually the father of the 2965 Supes) accidentally ripped open a dimensional warp while saving Earth from yet another comet.  Their rocket went into the dimensional warp where Muto was born and:

He forces Superman to dive into some water to save three children from drowning. Supes discovers too late that they are not real children at all, but androids:

Fortunately Superman is able to reprogram the android kids with his heat vision so they drag him to safety.

That pretty much sets the tone for most of the rest of the final chapter of the story.  Muto tries various tricks to get Superman surrounded by sea water. Oh, and at one point Muto aims a growth ray on everybody in Metropolis, which causes havoc:

Eventually Superman manages to trick Muto into attacking him near a lightning rod.  The lightning opens up another dimensional warp, which sucks Muto into it.

Comments: The decision to make the future Superman's weakness sea water seems kinda silly.  Basically crooks could just carry water pistols around with them to handle him.  Indeed, in a later World's Finest issue, the future Joker is shown on the cover downing Superman with a squirt from the trick flower in his lapel.