Semantics Surprise surprise motherfucker. You're talking about me (and a few others). I've posted here before and I wrote for the game between 2016 and 2018. Most notably the Fiona storyline and large segments of the Chapter 5 trial sub quests and the post-trial material. Also a smaller but still decent chunk of Chapter 6. I left because I couldn't split focus between it and larger projects.
So, could the remaining writers and coders who worked with Ker continue the project in his absence? Probably not.
Most if not all of the writing collaborators on the project worked on smaller segments of side content, and not on the main material. In fact, Ker did not give his former staff any kind of roadmap that would let people follow his vision. Any writers picking it up now would be mostly doing the equivalent of official fanfiction.
None of us besides those tech side worked in engine so much. The games' repository still exists (presumably) but is untouched for a long time. I actually think this is the part that members of his team could replicate if they tried.
Furthermore, none of us did any work in 3dCG. Now, someone with decent computer knowledge could pick up the program or even find some of the materials he did. But, it's an old system and not so easy to just go into the way newer modeling programs are. Also, Ker was just a very experienced modeler. Made thousands of pictures over a decade of work. You can have the same tech knowledge, the same files at your disposal, and still make much worse pictures from lack of image composition in the medium sense.
Also, I've spoken to members of the team who still are active, and most agree that it wouldn't
feel right. Some games with a team of people are a true team game. But, Harem
IS Ker's game. It doesn't exist without him. There is just no desire to attempt to forge on without him.
All anyone can do is hope the man is okay and doing well wherever he is.