User blog comment:Western Gen/Speculations for Season 12/@comment-5746209-20131118183625/@comment-5746209-20131120183524

Well I don't know the source, but I've seen several (different) anons and editors state Burnie has confirmed this (so it's debatable). As for the possible characters to return, I'll list the major ones:

Blood Gulch Chronicles Characters: We know Aliens aren't playable on Halo 4, so Junior is very unlikely to return. Sheila has the highest chance of returning, as she's still alive, just operating at minimul capacity at Valhalla. The fate of Vic and Andy is still unknown, so they have a possiblilty to return. Lastly, Sister's death was never shown, so Rooster Teeth can find a way to bring her back.

Recollection Trilogy Characters: Out of the major characters we haven't seen in a while, the only one still known to be alive is the Chairman. Command/479er's and the Counselor's fate is also unknown after Project Freelancer was disbanded. Thus, this leaves the possiblilty that these 3 characters could return.

Project Freelancer Saga Characters: The only major characters who have a possibility of returning are the last 3 Insurrectionist (Demo Man, Girlie, and Sleeves), as their status is left unknown. Surprisingly, one anons keeps mentioning Utah will appear in Season 12, as they state Burnie hinted at the characters return.