Why wasn't Jango Fett ever replaced as the Republic's clone template during Star Wars: The Bad Batch confirms that Jango Fett's original host DNA used to create the Republic's clone army was in a state of degradation. However, it seems as though the Kaminoan cloners knew this was happening even during the middle of the war with the Separatist droid armies, so why wasn't a replacement donor chosen? Here's a few reasons why, as well as why a replacement template may soon be found in the new series.
The death of the bounty hunter Jango Fett during the events Kamino's prime minister Lama Su in the premiere episode of Clone Wars' third season, when Jedi Master Shaak Ti expressed her concern with the latest clone recruits that were produced, such as the unorthodox nature of Domino Squad.
Surprisingly, Lama Su did recommend to Shaak Ti that the Republic begin a search for a new host template apart from Jango Fett, though it seems as though Domino Squad's eventual ingenuity and success during training put the Jedi general's mind at ease. However, the end of the Clone Wars has come and gone by during the events of The Bad Batch, and the Kaminoans' future with the newly risen Empire is in jeopardy. Governor Tarkin wants to phase out clones in favor of using enlisted troops to serve as the Empire's primary infantry forces – what would become the Empire's notorious stormtroopers – though Lama Su and head scientist Nala Se are making plans to secure their relationship with the Empire. With Fett's template nearing total degradation, it seems as though their best hope is going to be using the enhanced troops of Clone Force 99 as new templates instead, for a number of reasons including their skill and specializations.
It seems as though the key reason Jango Fett was never replaced was due to Shaak Ti's belief that the clone troopers being produced were acceptable as they were, even with the template being stretched. While the Kaminoans revealed that there's no one way to make a clone, their efforts appeared to be satisfactory. That being said, had the war gone on longer than its three years, perhaps the Republic would have scouted for a new host replacement if the quality of the clone trooper's production continued to fall. However, Shaak Ti saw every clone as a living human being (as she should as a Jedi), which motivated her to value the clones' lives more than the cloners did, meaning that she held a greater tolerance for any imperfections found.
That being said, the Jedi and the Republic are no more, and Kamino is ready to take drastic measures in order to make sure they survive. Given Tarkin's interest in recruitment and Project War-Mantle, it seems as though the only way for the cloners to make themselves attractive is to use the Bad Batch to make a whole new army of super-soldier clones, though it does seem risky to try and create clones from clones. In any case, new details and insights are sure to come as The Bad Batch continues on Disney+, offering a whole new chapter into the Empire's rise in the Star Wars galaxy.
