Therefore, No. 5 Killer (let's call him Bob) moves into the #4 slot.
-- No. 3 Killer (Hanada) torches No. 2 Killer (Sakura)...but No. 2 Killer (Sakura) is actually shot dead a few seconds later by the yet-to-be revealed No. 1 Killer.
Bob moves into 3rd place.
-- No. 1 Killer shoots No. 3 Killer (Hanada)...but not before No. 3 Killer (Hanada) shoots No. 1 Killer.
So, without lifting a finger, No. 5 Killer (Bob) is now the new No. 1 Killer.
^Except No. 3 Killer Goro Hanada doesn't die, so Bob would be No. 2 (still pretty good though, ha).
In Seijun Suzuki's pseudo-sequel to this film--"Pistol Opera"--Hanada is indeed still alive, now ranked as the No. 0 killer, alias "The Champ" (an allusion to the final scene of "Branded to Kill"; however the character is not played by Shishido, the casting was apparently beyond Suzuki's control), although his presence in the organization is such that even though his actual skill and proficiency as a hitman is questionable, he's untouchable.
There's also new set of killers, all with special nicknames and unique M.O.'s--for instance the No. 1 killer, alias "Hundred Eyes," uses a sniper rifle, shooting his victims in a specific part of their brain that leaves them as smiling corpses(!). _____ Yeah, I'm so bad I kick my own ass twice a day. -Creeper, the Hamburger Pimp from "Dolemite"
"Pistol Opera" is actually less like Suzuki's sensationalist Nikkatsu era work, and closer to the fever-dream-like quality of his later Taisho trilogy like "Zigenurweisen" and "Kageroza." These aren't Yakuza films, they're closer to perhaps surrealist cinema--like Bunuel minus the satire and anti-bourgeois sentiment. Either way I'd recommend it seeing as how you've got impeccably good taste in having enjoyed his masterwork "Branded to Kill" and personally "Pistol Opera" is the film that's sparked my interest in a man who has gradually become my favorite director of all time and sort of an obsession that I'd previously reserved for the likes of Robert Mitchum and Jean-Pierre Melville (my second favorite director of all-time).
Also to add to my previous statement, Goro Hanada was indeed intended to have lived in the end. According to an interview with Seijun Suzuki his survival was his ultimate rebellion against genre conventions, as pretty much every anti-hero in every crime film ever meets a tragic demise, he lives in dishonor opposed to dying with honor and dignity like your average "Yakuza" (which he really isn't). I read the finale as a perverse "happy ending" in that Hanada's life becomes a fate worse than death. ______ Yeah, I'm so bad I kick my own ass twice a day. -Creeper, the Hamburger Pimp from "Dolemite"