In the anime, supposedly Boruto was given a medicine to stop his transformation into Momoshiki. But in episode 225 of the anime, Sasuke and Sarada talks about if she had the determination to stop Boruto if he gets out of control.
Can Boruto still become Momoshiki?
Yes, Boruto can still become Momoshiki. Amado himself (roughly stated in my words) that:
This is a drug I crafted with the aim of weakening the Byakugan. Don't ask for the details. The origin of the Byakugan lies in the Otsutsuki. So, taking a Byakugan-weakening drug may slower the Otsutsukification, but not stop it entirely.
The medicine will slower but not stop entirely the process of the Karma seal. Whether Sasuke or Sarada have the determination to stop Boruto is not relevant, unless he is killed by them and the Karma process of will fail as Boruto is an incomplete vessel.
It's put into play exactly how the medicine affects Boruto, as when he was able to control the form that would typically show Momoshiki is controlling him (in chapter 65.) Note he doesn't have a horn, both of his eyes are open, and Boruto is in full control.
