With the recent reveal in Boruto about the true nature of the Karma Seal, many fans have noticed that it bares striking similarities to Orochimaru's Curse Marks. The Karma's purpose is to overwrite the genetic makeup of its host in order to create a suitable vessel for the Otsutsuki to reincarnate into. This process grants users access to abilities they previously did have as well as makes their bodies much stronger. With those qualities it is no surprise fans find the Karma Seals reminiscent of Orochimaru's creation.
Orochimaru's Curse mark is different in multiple ways, with these differences being key to his future role in the story. His Curse Marks operate by merging Orochimaru's own senjutsu chakra (the same chakra used in Sage Mode) with user's own, causing a tremendous increase in physical ability and chakra. This boost allowed Sasuke to fight Naruto's one-tail form on equal footing.
Much like the Karma Seal, the Curse Mark has two separate stages of power, a first and a second, and they each operate quite similarly. In the first stage, both seals spread markings throughout the users body, stemming from the seal itself. In this state, users of both gain increased physical abilities and chakra, albeit through different means.
The second state operates in a similar fashion to the first, with both undergoing physical transformations while gaining greater power. The difference is that the Curse Mark causes specific transformations that are at lease somewhat unique to the user, while the Karma Seal's transformation makes the user look like a specific Otsutsuki.
Another aspect to the Curse Marks that's important to note is that Orochimaru's consciousness is held within it to some degree, also like the Karma. However, while the Curse Mark can corrode the mind of its owner to fall under Orochimaru's influence, the Sannin cannot overtake the host like the Otsutsuki can. Rather, this is a completely separate process that Orochimaru has to perform himself on the host.
With these similarities, it wouldn't be surprising for Orochimaru's role in the series to grow into something much more than it currently is. With only a relative handful of appearances in the anime and none in the manga, it would definitely shake things up to a degree. Orochimaru has maybe the greatest understanding of the biology of a shinobi, and Konoha's newest resident Amado is utmost expert on the biology of Otsutsuki and Scientific Ninja Tools. Together the two scientists could make leaps and bounds in regards to whatever they would be researching.
Orochimaru's past with Sasuke as well as his overwhelming power also need to be taken into account. After all his research on the Sharingan and Rinnegan, there is a chance that he could aid Sasuke in getting his left eye back. Also, as someone who has chosen to follow Sasuke, Orochimaru would be more forthcoming with aiding him than with anyone else, making this a more likely eventuality. And with his strength being as great as it is and Konoha currently at its weakest, Orochimaru could easily remedy this problem himself.
While Orochimaru doesn't have any history with the Karma Seals, his own Curse Marks should provide him an understanding of how they work greater than almost anyone else's. This would allow him to help teach Boruto how to utilize it better and maybe even contain it. With Mitsuki being one of Boruto's closest friends and Orochimaru's child, the Sannin might feel more inclined to help out his son's friend, especially as he is Sasuke's pupil.
Also, with Katasuke being nowhere near Amado's level, Orochimaru might end up being the only one who could keep up, as well as being the best person to keep an eye on the suspicious Kara defector. Amado even has some history with the Sannin -- Koji Kashin is a clone of Jiraiya, after all -- so Orochimaru might want to have some words with him already. While the relationship between himself and Jiraiya was complicated at best, it's unlikely he'd be completely fine with Amado's actions towards his ex-teammates corpse and legacy.
Unfortunately, even in the manga Orochimaru's role is minimal at best currently, so if there are plans to bring him back they definitely aren't obvious. However, with Boruto's increasing focus on Scientific Ninja Tools as well as foes with bodily enhancement, Orochimaru's return would make the most sense if it were to happen now.
