There’s still a lot of speculation about the cast for the next challenge, but it looks like there will be a lot of newbies/ rookies in the cast. In fact, there has been very little speculation about veterans that may be on the cast. However, it looks like Wes will be on the next challenge if this tweet from Johnny is accurate.(screenshot courtesy of Jaz22 on ChallengeForums)
The lack of veterans has many people wondering what the format of the challenge could be. It is widely believed, though not confirmed, that the challenge will be Battle of the Seasons-esque. Teams will likely be divided based on their season of origin.
Challenge forums also has a list of speculated cast members. Check it out here