Bring back the old Spartan-IIs as shown in the books and show the Spartan-IVs (including Commander Sarah Palmer) whose boss when it comes to fighting against the Covenant. They are a vital asset to the Halo universe and it would be awesome to see them fight alongside Master Chief in the campaign. I mean, three people playing as the characters in the Campaign (Linda, Kelly and Fred), who wouldn’t want that?
343, it’s time.