WARNING: The following contains spoilers for Chapter #55, “Legacy,” of Boruto: Naruto Next Generations by Masashi Kishimoto, Mikio Ikemoto, Mari Morimoto and Snir Aharon, now available in English from Viz Media.
In Chapter #55 of Boruto, change is definitely the order of the day. Naruto's lost Kurama, Sasuke no longer has his Rinnegan and last but not least, Isshiki Ōtsutsuki is officially dead. It seems like the shinobi world is safe again, but Isshiki throws a wrench in that notion just before he dies by making Code his successor.
However, as this passing of the baton occurs, it becomes clear that things didn't have to be this way for Isshiki. The tyrant had the ultimate weapon all along and, had he let go of some of his internal issues, he wouldn't have let it go to waste as he did.
There's a problem with this, however, because it leaves one wondering why Isshiki didn't try to create more minions like Code while he was alive. We know Code was a failed Vessel, one of many prototypes that Isshiki didn't deem perfect like Kawaki. But he could have blessed them with the mark or copies of it instead of discarding them. Many marks can exist after all, as Jigen and Kawaki had the black marks for Isshiki to rewrite their bodies, so the likes of Boro and Delta could have been given this tool.
It would have made them stronger and helped them take Konoha out, thus protecting Kawaki. Once that happened, Isshiki could have fed him to the Ten-Tails and gotten chakra fruit for everyone. As for other clones, Isshiki could have used mind-control jutsu or science tools to keep them in line, deploying them when he saw fit. And make no mistake, as much as some Kara members were traitors, Isshiki would have been the one to activate the mark, and so he could have built a failsafe into it to eliminate traitors.
In fact, this would have given him a hold on their body as he had with Kawaki, so it really is a perfect way of making super-soldiers and keeping them in line. But by going with robotic puppets, cyber-shinobi like Boro and co. whom he didn't trust fully, Isshiki alienated his team and shot himself in the foot. It created jealousy, turmoil and civil war, which all helped to weaken Kara. All Isshiki had to do was share the power in life. Instead, he's reactive and sharing it in death, when he won't be there to guide Code or bask in the spoils of victory.