Co-op WC was definitely always a dream. But that would be very challenging for the narrative. The story immediately becomes an ensemble piece, but for an ensemble to work well, you've got to have a varied cast with differing attitudes, opinions, and skills. And the more you stylize the characters, the weirder it is for players to jump in. I suppose a game like Left 4 Dead attempts this and succeeds, but there isn't much story, it's more like hearing the characters have funny banter. That works during gameplay sequences, but during cutscenes? Or back on the carrier? Would I be able to interact with my friends? And how would they interact with the rest of the cast? Would it be more like a FPS onboard the ship, as opposed to a cinematic, directed filmic sequence? That would sacrifice a lot of the "I'm in a space opera" feel that the franchise strove to create. Perhaps, more like Mass Effect, where once you engage in conversations, the camera begins to shoot standard cinematic coverage. But, this would then leave the question: would the NPCs react to each player character in the same way, or would they react to my character differently than your character? And if you weren't playing, how would they think or feel about that character? Or would that character cease to exist?
These are the big questions about multiplayer. I would love to see something like that actually work out. But it would be a challenge to allow two or more people to drive the direction of the narrative forward.
I've never played any of the Halo games as a Single Player, I've always played co-op, and the story never really acknowledges that suddenly there's TWO master chiefs, and that's weird. But the game is still fun, and it's great to have a buddy there to have your back.
I think crafting a multiplayer WC adventure would be more work than a studio would be willing to undertake. I suspect we're likely to see skirmish and team based side games, but, as a side event to the main thrust of the game, which would be an immersive single-player space combat interactive cinematic experience.
I actually really thought Prophecy played very well. I enjoyed the button pushing aspect of the game greatly, but the story just felt clunky and uninspired. It felt like a direct to video sequel in that regard, even if the gameplay was a step up. Also, graphically, it was amazing at the time. Although, again, the decision to have a pulse-pounding electronic soundtrack instead of the familiar orchestral score seemed odd. It also wasn't Chris Roberts. Not that I believe the guy is a deity or something, but I always felt that the game was very much somebody else running with the intellectual property and not really carrying the heart. That said, in my ideal world maybe Prophecy wouldn't be completely erased, but would be something that could be heavily adjusted to be more... well... better. Or it could stand as an alternate universe adventure, like Super Wing Commander or something. I dunno. It doesn't marry very neatly to the Kilrathi trilogy or WC4.
The problem with returning to the Kilrathi war is that prequels are often narratively less engaging. I'm not saying across the board, but frequently. There's no hope of my character ENDING the war. I know who does that, and how it happens. But I do believe that the war was long enough and with enough twists and turns that a compelling story could still be fished out of the Kilrathi conflict. I'm just not sold on the idea just yet.
So... expectations are very high. That will be a challenge for our boy Chris. But, really, we've ALL been hungry for some more WC. So, I hope he's up to it!