Contrary to popular belief, Superman is so much more than Clark Kent, which is why Nightwing and Starfire's son Jake deserves the mantle next. More than just powerful, Jake represents the hope and optimism which every Man of Steel should strive for.
Though Nightwing is, justifiably, most associated with Batman, Superman is just as much a mentor as the Dark Knight. It's easy to forget that Superman gave Nightwing the idea for his name. In a way, Dick Grayson is the natural combination of Superman and Batman. Dick has Batman's lack of powers and critical thinking skills combined with Superman's boundless optimism and ability to inspire hope in others. On the other hand, whatever powers Ngihtwing lacks are more than made up for by Starfire. While no one would mistake her for a Kryptonian, her super-strength, flight, and energy beams do give her more than a few of the Man of Tomorrow's most famous abilities. While the two are currently broken up, there are several alternate futures Nightwing and Starfire have a kid such as Nightstar from Kingdom Come. One of the darkest alternate futures however produced a hero who more than earned the title of Superman.
In Nightwing: The New Order by Kyle Higgins and Trevor McCarthy, the future is bleak for DC's metahumans. As war erupts between heroes and villains in Metropolis, Nightwing is left with no choice but to depower the world to save those caught in the war's crossfire. In the aftermath, metahumans are outlawed and Dick leads an anti-metahuman task force, which leads to Dick and Kori's separation. Eventually, the former Nightwing is forced to confront the world he created when his son Jake develops powers. With the help of the metahuman resistance led by Starfire and the remnant of the Titans, they discover that Jake is the cure to restoring the world's powers. Inevitably it leads to a big battle between the Titans and the anti-metahuman task force that ends with a bomb detonating that gives metahumans their powers back. Fortunately, Jake helps save everyone who would have been caught in the blast.
Though Jake never officially becomes a superhero, his actions and potential show that he can be a Superman like no other. When Superman first premiered, he was a hero of the New Deal, he represented an incredible spot of hope in a time when hope was hard to come by. However, as Superman's origins increasingly crept up in the years, this important context for Superman's arrival was lost. Jake, on the other hand, has his origin inextricably tied to a tense era where metahumans are demonized and everyone is paranoid their neighbor could have powers. Jake however is the hope that unites the world in a way that Clark Kent hasn't in decades. It can be argued that Jake is the template for Jon Kent's Superman who fights modern problems like Climate Change.
Unfortunately, Nightwing: The New Order is the only reality where Jake shows up. Still, with the infinite possibilities of the DC Universe, it's entirely possible for Jake to make a reappearance. Given Nightwing's ties to Superman and Starfire's incredible powers, it's not a stretch to suggest that an alternate Jake could come back to DC Comics as the next Superman.