Just saw this new interview with Bonnie Ross on the future of Halo, mainly talking about Halo 5. She was obviously being deliberately vague in some of her answers so as not to give things away too early. This hint about the Halo 5 campaign certainly caught my attention, though (WARNING: Halo 4 ending spoilers):
> For us, it really was about Halo 1, 2, 3, 4 - you know, 4 kind of started his hero’s journey where he’s basically been a pawn of the UNSC from being a 6 year-old boy, kidnapped, made into a super soldier. The way we looked at it was, at the end of Halo 4, he’s lost his closest companion so he’s questioning everything.
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> For us, going into Halo 5, we’re asking who he is as a man, not as the super soldier. When he’s thinking about what he wants to do, thinking for his own reasons on why he’s fighting, and who he’s fighting for, I look at it more as this being the start of his journey.
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> Halo 4 was the start and Halo 5 is pretty exciting: we’re not really talking about the campaign yet, but it is a continuation, but a very different story for Master Chief.
It also looks like the interview took place after the Halo 5 multiplayer leaks but before the MCC launch (I’d assume it was at Halofest), so the matchmaking issues aren’t discussed.