From what I understand the reason Fan Favorite Game Changer Sierra Dawn-Thomas is there is because she was just an alternate who took the place of Natalie Anderson who had to drop out last minute.
I'm not in love with the cast but it seems like it could be a good group, and in sure it will still be a fantastic season. I posted al of my thoughts on the cast in the Survivor thread a while back, but overall I'm most excited for JT, Tai, Tony, Debbie, Varner, and Sandra.
If anything my fear is that the season is going to be too short (it's starting really late!) and too many people are going to be given a purple edit (Like Wiglesworth in Cambodia...she was one of the stars of the premier, and then we didn't hear a thing from her for the next nine episodes until her elimination). I don't know why but I have this sinking feeling that JT is going to be given an invisible edit unless he does really really well.