Star Wars continuity, the Expanded Universe (now called Legends), had its own New Jedi Order, but so far, its closest canon counterpart is Luke’s generation of Jedi, as referenced in the sequel trilogy. There are several reasons why this theory for canon is plausible, including reasons why Grogu may return to Ahsoka’s guardianship and why it must be the two of them, rather than Luke, who create a new and improved Jedi Order.
In Return of the Jedi. The Legends version of Luke retains characterization that is consistent with his behavior and personality in the original trilogy. Luke continues to develop and grow as he gets older. His many victories and failures teaching him to remain humble and continue to redefine what it means to be a Jedi. Just as Luke refused to follow advice from the old guard Jedi when he felt it was wrong (as seen in Return of the Jedi), Luke in Legends takes this a step further and creates the New Jedi Order, which is fundamentally different from the prequel-era Jedi Order.
In the prequel trilogy, the Jedi Order is largely disconnected from the people of the galaxy, headquartered almost literally in an ivory tower, and used as a political tool of the Republic with almost no oversight. Jedi were taken from their families as infants and taught to suppress their emotions and were forbidden from forming attachments or owning possessions. In Ambush at Corellia, Luke and Mon Mothma discuss the flaws of the old Jedi Order, and how Luke intends to not repeat the same mistakes with his new Jedi Order. Luke’s New Jedi Order allows beings of any age to voluntarily. They’re encouraged to live lives outside of being Jedi, and are allowed to own possessions and have romantic relationships. Luke’s Jedi controlled emotions instead of suppressing them or being controlled by them. Unfortunately, the canon version of Luke, despite his arc in Return of the Jedi, did not learn from the Order’s mistakes (or his own), and he rebuilt the Jedi, only for them to be nearly destroyed by Ben Solo.
Luke Doesn’t Train Grogu All the Way
There is already strong evidence that Star Wars: The Last Jedi, Luke states that he trained Ben Solo along with twelve other students in his Jedi Temple. Most of the students were seen in the comic series The Rise of Kylo Ren, and all but Voe, Hennix, and Tai were killed when Ben Solo destroyed the temple.
Grogu, of course, is one of the protagonists of The Mandalorian, and appeared before the comic was published. From an out of universe perspective, it’s unlikely that he’d be killed unceremoniously and off-screen even if he was among the few unseen apprentices of Luke’s at the time. Because of this (and the fact that he’d still be an infant at the time of Ben’s turn to the dark side), Grogu wouldn’t have been fully trained as a Jedi and thus could be one of the first of the new iteration of the Jedi Order.
Grogu Requires More Attention Than Luke Can Provide
As a member of Yoda’s species, Grogu doesn’t age the same way as most humanoids. Though he’s lived over 50 standard years, he is, for all intents and purposes, still an infant. Because of this, Grogu requires far more time and care than a typical Jedi student. Moreover, Grogu’s slow aging process means that he’s likely to remain an infant for a long time, necessitating constant care and attention for potentially decades.
As evidenced by The Rise of Kylo Ren, Luke was the only one teaching and watching over his students (though he was occasionally ed by Lor San Tekka), so it’s unlikely that Luke could properly train all of his students and simultaneously take care of a Force-sensitive infant. One possibility is that Luke and Ahsoka were co-leading the new generation of Jedi, and they’d each alternate between teaching the students and caring for Grogu. This also creates the possibility that, if Luke and Ahsoka both believe that a new kind of Jedi Order may be necessary, Luke remains with his students and trains them as classic Jedi, while Ahsoka volunteers to raise Grogu as part of the new iteration.
Ahsoka and Grogu Can Fix the Jedi in a Way Luke Can’t
As demonstrated by The Last Jedi, Luke, unfortunately, did not end up breaking the cycle of the old Jedi Order nor did he learn from his own failures in his youth. Luke learns all he can about the Jedi of old and ends up repeating their mistakes once again, driving him into exile and depression. For this reason, Luke is not the right person to create a New Jedi Order that redefines the concept of Jedi, unlike his Legends counterpart.
During his exile, Luke explained to Rey that the Jedi need to end due to his belief that the institution is ineffective at best, and worsens conflicts at worst. It’s possible that Luke, becoming aware of the possible inadequacy of the Jedi Order during his rebuilding of them, prepared a contingency in the form of Ahsoka and Grogu, tasking them with creating a new version of the Jedi regardless of whether or not his reestablishment of the old order succeeds.
Ahsoka and Grogu Can Make a More Perfect Jedi Order
Ahsoka, on the other hand, was once a prequel-era Jedi, but voluntarily left the order during the Clone Wars after being framed for bombing the Jedi Temple. The Jedi Order, for the most part, had no faith in her and was eager to cast her out of their ranks before she was proven guilty. For the rest of her life, Ahsoka became an und Force who lived by her own set of ethics and guidelines. Like the Legends version of Luke, Ahsoka is a humble, down to Earth warrior who, if tasked with redefining Jedi, would no doubt create a more emotionally healthy and effective version of the order.
Ahsoka has also seen far more of the galaxy and the Force than the canon version of Luke. Having been to the mysterious world of Mortis and the plane known as the “World Between Worlds,” Ahsoka could potentially teach Grogu more of the Force than Luke could. If Lucasfilm wanted to emulate the Marvel and DC multiverse stories, they could have Ahsoka visit the Legends universe via the World Between Worlds. There, she’d learn about the original Expanded Universe’s New Jedi Order from wiser Jedi like Mara Jade or the Legends version of Luke.
The Future of Star Wars Needs a Bigger Galaxy
Ahsoka starting a New Jedi Order with Grogu allows them both to survive Star Wars: The Rise of Skywalker). It’s also possible that Luke was in some way involved in Ahsoka’s decision to create a new kind of Jedi with Grogu as, once again, a contingency. In this case, it would be a safeguard against his Jedi Order failing and also the possibility of it being destroyed. Of course, both of these exact fears do come to fruition making the possible contingency a wise decision by Ahsoka and Luke. From an out of universe perspective, it allows Ahsoka and Grogu to potentially include Rey in their creation of a New Jedi Order, and further connecting The Mandalorian to the Skywalker Saga.