The truth about how Kawaki killed Boruto immediately began posing a threat to Narutos status as Hokage ever since he decided to keep the truth from the villagers of Konoha. But now that threat might actually become a reality much sooner than expected.Konoha never truly trusted or agreed with Narutos decision to let Kawaki stay in their village because the boy had originally been raised by the villainous Kara organization to serve as the future vessel of Isshiki Otsutsuki. But Naruto ignored their disapproval and continued to care for Kawaki because his own past of being ostracized allowed him to sympathize with Kawakis current status as a social pariah. The prospective revelation that Kawaki actually killed Boruto would undoubtedly push the villagers over the edge causing them to demand the boys exile regardless of the fact that Boruto had actually asked Kawaki to murder him and that he actually survived in the end. But should Konoha ever learn that Naruto was aware of and actively tried to cover up the incident Narutos future as Hokage would definitely become uncertain.
Chapter 69 of Boruto just expedited the likelihood of that actually happening by Sumire Kakei overhearing the truth. After his clash against Code and the Momoshiki possessed fully Otsusuki Boruto Kawaki had fallen unconscious eventually waking up in Konoha to Naruto and Sumire. Although the Hokage asks Sumire to leave so he can have a private conversation with the boy she is still in the room when Kawaki quickly asks if Naruto will condemn him for killing Boruto. This news understandably shocks Sumire who isnt one of the select few Naruto with whom entrusted this knowledge and although anyone learning the truth could be problematic for Naruto this is especially the case because of Sumires history and feelings for his son Boruto.
Long before establishing their relationship Sumire always betrayed her true emotions for Boruto by how she acted around him getting especially flustered whenever anyone hinted that they knew how she truly felt about him. Their bond grew immensely when Boruto was willing to forgive Sumire for allowing herself to get swept in her familys past sins and attack Konoha an impressive display of loyalty that Sumire never forgot. This will undoubtedly serve as a major force against Naruto in the coming chapters even though Naruto is Borutos father and exposing him could hurt Boruto by proxy. Sumires romantic feelings for Boruto augmented by her undeniable desire to repay him for his kindness could likely compel her to act in a way that she feels will serve Borutos best interest. Even if she doesnt act maliciously the likelihood of her sharing this information with another villager at Konoha who is especially critical of the Hokage could result in a more brutal spin of the truth that puts Naruto in a negative light.
Basically the prospect of anyone not just Sumire outside of Narutos inner circle learning the truth about how Kawaki killed Boruto could prove disastrous. Sumires bond with and feelings for Boruto just make her role as the potential leaker appear much worse. Additionally the fact that this latest development now puts more importance on Sumires earlier storyline and her relationship with Boruto certainly fuels speculation about Narutos future as Hokage even further.