The following contains spoilers for the story "Two Birds, One Stone" from Batman #127, now on sale from DC Comics
The supporting story in Batman #127 (by Chip Zdarsky, Belén Ortega, Luis Guerrero, and VC's Clayton Cowles) sees Catwoman uncovering the truth behind the Penguin's apparent demise. It turns out Oswald is alive and well, running a flower shop in Metropolis. Despite a very messy exit from the Gotham underworld, it looks like The Penguin has achieved what no Batman villain before has ever managed: retirement. After Oswald faked his own death, framing Batman in the process, a war broke out among his heirs, with all but two of them being assassinated. Simultaneously, a gang war broke out over the control of the Penguin's criminal empire.
In all that confusion, it was simple for Oswald to slip away, using a crooked bookkeeper to funnel himself enough money to set up a new life in Metropolis. Here he hopes to break the cycle of violence, and it looks like he might just have succeeded. It's not surprising that of all Batman's rogues, Penguin is the one to have successfully recognized this pattern and extracted himself from it. He has always been the savviest and most rational of the Dark Knight's enemies, running his criminal empire with intelligence and ruthless efficiency. But whether these qualities can make his retirement happy and permanent remains to be seen.
Penguin is not the first villain to get out of Gotham City. He's not even the first to fake his death to do it. Batman Eternal #51 (by James Tynion IV, Scott Snyder, Ray Fawkes, Kyle Higgins, Tim Seeley, Álvaro Martínez Bueno, Raúl Fernández, June Chung, and John J. Hill) saw the villain Cluemaster appear to die at the hands of Owlman, only to be discovered alive and well by his daughter Stephanie Brown (the current Batgirl). Like Oswald, Cluemaster faked his death to escape the cycle of fighting Batman. Unlike the Penguin, however, Cluemaster is continuing his life of crime, just in a different city.
Perhaps a closer comparison to Oswald's retirement is the retirement of classic Batman villain Catman. Fed up with being treated as a joke by his fellow criminals, Thomas Blake retired to live with a pride of lions in Africa. Blake had recognized the trap he was in, bemoaning always being on the run and never enjoying the spoils of his crimes. Unfortunately for him, his retirement was short-lived, as the Secret Society of Super-Villains dragged him back to a life of crime. Similarly, Two-face's many retirements have been short-lived, with the character always ending up as a villain again. This is the pattern for any rogue's apparent retirement.
There is, however, a group of villains who break this pattern. Unfortunately, The Penguin doesn't seem interested in joining their ranks. Several key Batman rogues seem to have left their criminal activities behind for good, but not in order to retire. Instead, these supervillains have attempted to be their own kind of heroes. The prime example being Harley Quinn. She had a personal revelation, realizing the harm her actions had caused and decided to attempt to make amends.
This doesn't seem to be on the cards for The Penguin. As Batman #127 shows, he has no regrets about his life of crime, no qualms about keeping his ill-gotten gains, and no love to spare for the Bat-family. On the contrary, his final words in the issue see him encouraging his successors to destroy the Dark Knight who made his life hell. It may be these very successors who allow The Penguin to enjoy a quiet retirement. There is after all one more group of rogues who have permanently escaped Batman: those who have passed their title down to the next generation.
Most notable among these would be Basil Karlo, the original Clayface. His exit from Gotham after the events of Batman #981 (James Tynion IV, Eddy Barrows, Eber Ferreira, Adriano Lucas, and Sal Cipriano) has been relatively permanent, only returning to defend Gotham during the events of "Fear State". Karlo's passing of his alter ego to Matt Hagen has allowed the former actor to enjoy a quiet retirement, while a Clayface still remains in Gotham. Perhaps with Oswald's children taking over his criminal empire, he can enjoy the same peace.