It appears the highly anticipated Halo TV series for Paramount+, produced by Steven Spielberg will be creating its own canon for the John 117 Spartan character - canon separate to what has previously been previously established in game lore. During a video interview with 343 Industry's head of transmedia Kiki Wolfkill, it was acknowledged that the Halo TV series will operate on a new timeline dubbed the Halo Silver Timeline. Here's what Kiki had to say:
We do have some context and perspective that is different from some of those stories that we’ve experienced or read about in the games. We’re referring to this as the Halo Silver Timeline as a way of differentiating it from core canon. And both protecting core canon and protecting the television story, and by that I mean being able to give ourselves the chance to evolve both and for both to be what they need to be for their mediums without colliding with each other.
To have the series separate to what's been established may sound like an odd move since there is plenty of lore left to be explored within the existing Halo universe. The official synopsis for the Halo TV series does still involve Humanity's war with the Covenant and does involve some key characters of the same names, but the plot seems devoid of any mention of Forerunner story arcs - which suggests to us the timeline for the series will predate the timeline beyond Halo 3. It will be interesting to see what aspects carry over between the two timelines when the series airs next year.