It turns out the baker's dozen that was the Transformers Writers Room last year was really just an actual dozen. From The Walking Dead creator Robert Kirkman while at SXSW 2016: “I have to say, I was only in that room for a day before I found out that I was having my throat surgery that kept me out of Comic Con.”
Not really major news since his Walking Dead, Outcast and likely future TV responsibilities would have prevented him from writing a Transformers script anyway. This just puts a nail in that particular hope. About the only negative as I see it is Kirkman was one of the few writers in the room that could consistently keep a focus on characterization and story while incorporating spectacle. Based on current info the 12 writers whose two week cram session will influence the next dozen or so years of the Transformers Cinematic Universe are Art Marcum & Matt Holloway (Iron Man, Transformers 5), Zak Penn (Pacific Rim 2) and Jeff Pinkner (Lost, Amazing Spider-Man 2), Ken Nolan (Black Hawk Down, Transformers 5), Geneva Robertson-Dworet, Steven S. DeKnight (Daredevil, Spartacus), Andrew Barrer & Gabriel Ferrari (Ant-Man, next animated Transformers movie), Akiva Goldsman, Christina Hodson (no released movies yet) and Lindsey Beer (no released movies yet).