I think that JD/Del will die on the first act on Gears 6 because TC is too lazy to deliver good story (no DLC story on Gears 4 and at the moment no DLC for 5), so they just need to do a few changes in cinematics and chat and after that the game is the same for everyone, regardless of their choice.
Or they can give them the “alternate ending for Clay Carmine”
*While Kait and JD/Del are thinking about how to fight the Swarm from a different angle, they remember JD/Del
Kait: I miss JD/Del. I wanted to spend more time with him, not fighting this war, just spending time doing something different…
JD/Del: I really miss him. So many adventures, perils and…
JD/Del face is covered by tears, He is so concentrated on the memories of his friend that he didn’t hear Kait saying “Watch out!!”
A banana peel was in the floor. JD/Del slips and he falls and rolls down stairs. He hit his head against a golden statue of Mina Jinn, and he dies instantly.*