I do think they are going to find a way to move on from John, though. I bet he's around for Halo 6 in some capacity, and then he gets retired from the games, other than maybe brief cameos in some manner as fan service.

Again, I have no hard evidence for this, obviously, it's just a feeling I have about the direction 343i is taking. I haven't yet worked out how it would make me feel. I like the Spartan-IIs and the Chief, but I don't think it's necessarily a bad decision for 343i to move on from that.

It seems like they're already really distancing themselves from it with the Spartan-IVs. It was so difficult for the S-IIs with a terrible survival rate, and all of the sudden it's totally possible with minimal effort and side effects to turn adults into Spartans. They can now potentially make anyone a Spartan, be it old characters (Buck) or someone completely new (Locke). Before they only had a limited amount of Spartans they could play with, now they unlimited numbers of Spartans they can create, so I don't really see the S-IIs sticking around for a long time in terms of being the main characters.