Boruto Uzumaki is the protagonist of Naruto's sequel, Boruto: Naruto Next Generations. Known to be a genius, Boruto's story was destined to be quite different from that of his father. Naruto was widely known to be a talentless ninja and, thus, his story was centered more around him working hard, surpassing everyone, and proving all those around him wrong.
With Boruto, things are quite different. Being a genius, Boruto certainly wouldn't be an interesting character by shonen standards. As such, bigger obstacles needed to be added to the story to make his character arc more interesting. At the very beginning of the manga, Boruto was made the vessel of Momoshiki Otsutsuki and since then, his fate is said to have been decided.
Momoshiki's Plan
It is no secret at this point that Boruto and Momoshiki are closely linked to each other. After the latter came to earth in search of the Nine-Tails, it was Boruto Uzumaki, along with the Kage and Sasuke Uchiha, who rescued Naruto. Following a difficult battle that saw both Naruto Uzumaki and Sasuke combine their forces and weaken Momoshiki, Boruto took it upon himself to show off his improved skill set. He went from being a disgraced shinobi to one who saved the world by defeating one of the strongest characters in the entire series.
Earning his father's recognition, Boruto was entrusted with a giant Rasengan that ended up killing Momoshiki. However, before he died, Momoshiki gave him a parting present in the form of Karma. The Karma is a powerful seal that contains the data of an Otsutsuki being encrypted inside it. Once planted successfully on someone, this seal slowly extracts itself and Otsutsukifies the body. In theory, it is quite similar to a compressed file being extracted and when the process is completed, the Otsutsuki can then be reborn.
Evidently, Momoshiki planned to return to life once his vessel, Boruto, had fully Otsutsukified. However, he ended up hitting a bump on the road. While Boruto had Otsutsukified up to 80%, his fight against Code proved to be quite lethal for him. When Kawaki stepped in, he ended up killing Boruto in order to prevent Momoshiki from taking over his body entirely. To prevent himself from fully dying, Momoshiki ended up saving Boruto by completing the Otsutsukification process.
The price for this was huge as it meant that Momoshiki would now fail to come back to life. However, Boruto's recent chapter revealed an interesting strategy that the Otsutsuki has now devised. It was revealed that Momoshiki can still take control of Boruto's body however, the catch for this is that Boruto's own consciousness needs to fade away. Thus, in case of severe emotional distress where Boruto's will breaks, Momoshiki can bring himself forth and take over the young Uzumaki's body permanently.
Boruto's Fate
Normally, Boruto is known to be quite a stubborn ninja, just like his father. His willpower is quite strong and he doesn't give up rather easily. In normal circumstances, it would be almost impossible for Momoshiki to take control of his body. However, under certain conditions, it could be feasible for him to take control. This is deeply tied to Boruto's fate which Momoshiki once foresaw. Being an Otsutsuki, Momoshiki's Byakugan is rather special. With it, he can even see the fate of people around him and he did just that moments before his death with Boruto.
According to him, Boruto's blue eyes would one day take everything away from him. Everyone close to him will be stripped of him and he will suffer tremendously. As the series went on, Momoshiki made his appearance on quite a few occasions and reminded the fans that the day Boruto loses everything is fast approaching. In the previous chapter, Momoshiki once again claimed that the most painful day for Boruto Uzumaki is almost upon him. Momoshiki also claimed that Boruto would want to give up living and when that happens, the chance would be ripe for him to pounce and take over his body.
It appears that the manga is rapidly heading to the point where Boruto loses everything precious to him. This could well tie to the time skip of the Boruto series. Fans know that at some point in the future, Boruto receives a deep scar on his left eye and goes on to take over Sasuke's role as the protector of the village. What's more, he even dons Sasuke's clothes and carries his weapons.
It is highly likely that this drastic change in appearance happens when Boruto's day of reckoning arrives. For Momoshiki Otsutsuki, this would be the perfect chance to take over Boruto's body, however, this attempt is likely to end in failure as Boruto was seen well in control when he fought Kawaki 4 years into the future. Nonetheless, the unfolding of Boruto's tragic fate will be quite intriguing to witness and, as the author has mentioned repeatedly, it is fast approaching.