What will happen to John? A question most people have asked themselves, referring to Halo or not. But I think it is time for a more detailed answer, please note that this is of course only my view.
Every story needs an end, so does Halo somewhere in the future. Because the Reclaimer trilogy is a saga now, maybe the end is pretty far away. My personal believe, shared with the voice actor of John is that John should have a hero’s death. Seeing where this story is going. I wouldn’t be surprised that John does what SPARTANs in general do, sacrifice his life for the lives of others (think of Kurt-051 for example). I still don’t think the Didact is dead, so that will most likely be the enemy.
We’ve also seen the teaser trailer about the Unnamed Forerunner Construct beneath some desert, the Youtube Channel ‘Halo5Follower’ had some nice ideas about that with which I agree. He thinks (based on Halo backstory) that this construct is 032 Mendicant Bias, you should watch his video about it. But sure to check out his other stuff, he has some interesting ideas.
I sure hope they don’t pull a ‘Reichenbach Falls’ on him, teasing if he died or not. I hope they just kill him on-screen when saving Earth and maybe even more than that. I would love to see John developing some more social skills, maybe even removing his helmet showing his crying face.