Sacrifice in the Sand: The Lesson of TBV's Second Arc
What the sacrifices in the second arc of Boruto TBV tell us about what comes next.

Sacrifice is not a new theme to the Boruto series. Starting in the first arc of Boruto: Naruto Next Generations (NNG), we're presented with two faces of sacrifice: Naruto bravely giving himself up to protect his son and the village in the face of Momoshiki's attack and Kinshiki sacrificing himself to fuel Momoshiki's destructive power. This duality permeates the series
Kawaki and Boruto are both Otsutsuki sacrifices, their own lives lacking in value to the parasitic aliens who need them to ensure their reincarnation and continued quest for godhood. First, they but vessels to the Otsutsuki, their bodies, identities, lives, and loved ones all meaningless compared to their purpose of reviving their hosts through Karma. As the series goes on, this becomes even more literal when we learn that one of them needs to be fed to the Ten Tails in order to grow the God Tree. For Momoshiki, the one who needs to be sacrificed is Kawaki; for Code and Eida, it is Boruto. In this context, their purpose simply exists to further the Otsutsuki species.
But another type of sacrifice is threaded through the plot, the choices characters make to protect the people and village they love. We see it time and again through the characters, Kawaki putting himself between Naruto and Delta's eye lasers, setting himself on fire to save them all from Momoshiki, offering his freedom to Code to save Naruto and the village. Boruto acts similarly, particularly after he knows the cost of having Momoshiki inside of him. He accepts that his death might be necessary to ensure the survival of others. This emerges in his conversation with Sasuke before fighting Isshiki, the kunai he puts to his own throat, when he asks Kawaki to kill him after Momoshiki rampages and almost kills Naruto. Both boys are willing to sacrifice themselves out of selfishness to protect the ones they love.
This theme continues into Boruto: Two Blue Vortex (TBV), and not just in the mindsets of the boys, Kawaki who has accepted that he's little more than a weapon to protect Naruto and Boruto who accepts Omnipotence to protect the peace in Konoha. From Moegi who gave up her life to protect a civilians during the Claw Grime attack to the shinobi who threw himself in front of Sarada, we see the trade-offs people make to protect those around them, particularly in the case of Sasuke, who was willing to become a traitor to the village once more and sacrifice his life to uphold Sarada's request to save Boruto.
However, in the second arc of TBV, not only do we see characters sacrificing themselves, we see the trade offs they make to protect those they love and the consequences that cascade from their actions.
Chapter 16: A Vibrant Life begins with Gaara, the Kazekage, standing in front of the three young people, including his own adopted son, who he's bound in sand to protect them from Matsuri. Holding his bleeding side, he continues to protect them despite having received a grave injury. Shinki defies Gaara's attempt to transport him to safety, breaking free of his sand encasing to protect his father. Though he manages to seal Gaara to prevent him from dying of his injuries, Shinki gets bitten by a Claw Grime, losing his freedom to the confines of a Divine Tree and initiating the creation of Ryu, a fifth Shinju.
This pattern continues once the mission to the Sand begins, Konohamaru, Sarada, and Mitsuki joining Yodo and Araya to betray and fight the Shinju. When Araya strikes a Shinju that was attacking Yodo, he loses his sword that could counter Ryu's power, taking away their team's advantage. When Yodo tries to bargain with Ryu, she offers to rat out Boruto for her teammates' freedom, thus getting herself killed (TBD).
Behind the scenes of these sacrifices that are seemingly personal decisions is Koji, pulling the strings to lead to his desired outcome. It's he who told Shikamaru to put together his particular team, fully knowing some of them might die for him to achieve his ends of Sarada utilizing her Mangekyo Sharingan (MS) and striking a blow against the Shinju. However, when Boruto realizes that he's been complicit in the death of one shinobi and is likely about to witness the death of his genin sensei, he puts himself in danger to save Konohamaru, appearing on the battlefield despite knowing full well that Jura, who is destined to kill him, is going to come after him.
Boruto's choice to appear on the battlefield is yet another sacrifice chosen out of connection that is going to have unexpected consequences. When Shinki decided to protect Gaara, Ryu was created. When Araya decided to protect Yodo, he lost his sword. When Yodo decided to protect her teammates, she both lost her life (TBD) and sparked Sarada's MS. As Koji told Boruto, if he had intervened at any point in the mission, Sarada's MS reawakening wouldn't have come to pass.
Boruto has given up his safety to protect Konohamaru, but the overall message of this arc so far has been that such choices have costs. Will Boruto lose his life (again), or, as Jura said, is he going to continue to be protected by divine intervention? Will someone else die as a result of Boruto's choice? Just as he's sacrificing himself for his sensei, will someone else sacrifice themself for Boruto's safety?
As Jura has said, love is dangerous, and that appears to be both true for Shinju and human alike. The question that is going to be answered in chapter 22 is what price will Boruto and the world pay for his decision to save Konohamaru.