The complete takeover of the Halo franchise by Microsoft and the dissolution of Bungie was a sad day for us all, but fret not, because even Microsoft wouldn't be so foolish as to drastically change what already works; over the course of one game anyways. Within 343i, many of the members from Bungie are still hard at work, including a few of the previous directors as well—as if anyone would ever get rid of someone like Martin O'Donnell.
And, I am actually extremely excited to hear that previous members of the former Pandemic Studios (Battlezone II, Dark Reign II, Full Spectrum Warrior, Star Wars: Battlefront) have moved over to 343i and are now working on Halo 4 and the Combat Evolved redux. They have produced spectacular games and woven incredible tales that are a pleasure to indulge in.
I look forward to the future Microsoft has promised us, we will be returning back to the story of Master Chief spread over what I can only expect to be a fantastic storyline spread out across a trilogy.