While Chuku Modu has been upgraded to a series regular, his character, Gabriel Santiago, isn’t guaranteed to survive The 100 season 7 - and it's theoretically possible he could give his life in the coming episodes. This wouldn’t be an unusual thing, as The 100 has a longstanding tradition of killing off characters when people least expect it, which has caused some problems for the show in the past.
The 100 season 7, episode 2, “The Garden” sees Gabriel travel to the planet Skyring (Planet Beta), having gone through the Anomaly to try and find Bellamy along with Echo (Tasya Teles) and Hope (Shelby Flannery). They manage to get through but have no idea how to get back. As part of their exploration, Gabriel discovers the Mind Drive of Colin Benson, who was part of Eligius III, the colonization mission that Gabriel was on originally.
Benson’s Mind Drive contained memories of him entering the code that activates the Anomaly Stone, which would allow everyone to return to Sanctum. Unfortunately for them, the memory viewer was destroyed before Gabriel could copy it down. Since that information is crucial to not only their survival but returning home, they need another way to get that information, and the easiest solution would, unfortunately, kill Gabriel in the process: he could upload Colin’s Mind Drive into his own body, resurrecting Colin but killing himself in the process.
There’s an irony to Mind Drives killing Gabriel, as they’re not only what keeps him alive but he was responsible for their development. The drives were originally meant only to store someone’s memories, but Gabriel and Russell developed a way to upload all of those experiences into a new body, essentially allowing someone to live forever. While he developed this technology, Gabriel eventually started to oppose its use by the Primes, the main antagonists of The 100 season 6, who used it to create a cult where people were willing to die to let the Primes live forever.
His opposition to the Primes would also make this a fitting end for Gabriel. He wanted to die long ago but was forced to be resurrected in this new body, a conflict he had carried with himself throughout season 6. This would allow him the opportunity to actually die while also unlocking the secrets of the Anomaly, which has been his life’s work. He can die, Colin would be resurrected in Gabriel’s body (allowing the actor to stay on as a regular), and he would die to help Echo, Hope, Diyoza, Bellamy, and anyone else impacted by the Anomaly storyline this season.
Gabriel has been set up as a major character for The 100 season 7, but this show isn’t shy about killing off characters when they’re no longer needed. Similar to how The 100 killed off Russell so quickly in the season premiere, Gabriel might not live that much longer to help the story move forward.