According to Sivertimes Cody Christian and Ryan Kelley will replace Arden Cho in the opening credits. According to Sivertimes Kira (Arden Cho) might not even come back. But according to Ryan's blog Kira will be back in 6B.
According to another Movie Pilot post. Tyler Posey and Dylan O'Brien's characters Scott McCall and Stiles Stilinski will be tested again. But this time not like the other time. It also says that we'll get a lot of Stydia (Stiles and Lydia) moments. Parrish (Ryan Kelley) will have a big storyline.
After season 6 (Season 7) Teen Wolf might be doing something much different. There have been rumors that said the whole older cast would leave and the younger cast would be the focus. Others say that some of the cast will leave and the most will stay. But a writer of the show said that Teen Wolf might be doing a Glee. But still different. And Jeff Davis said that if the show goes further than he expects (Season 7). He wants more time, like 60 minutes. No commercials. Or maybe 20 minutes if they go for the 80 minutes stuff. But that means that there will be 60 minutes of Teen Wolf every week. Well not every week. But what would they do? Scott McCall (Tyler Posey), Stiles Stilinski (Dylan O'Brien), Lydia Martin (Holland Roden), Malia Tate (Shelley Hennig), Kira Yukimura (Arden Cho), Theo Raeken (Cody Christian), Isaac Lahey (Daniel Sharman), Chris Argent (JR Bourne), Deputy Strauss (Aaron Thornton) and Derek Hale (Tyler Hoechlin, if he comes back) would be in another city, they would be spreid over 2 colleges, that would be in front of eachother. While Deputy Strauss will be moving to that new city, Chris will be there for Scott and Isaac. Derek would be there since Season 5 (if he comes back). They would all live in the same house, a big house. Except for the deputy. While Liam Dunbar (Dylan Sprayberry), Hayden Romero (Victoria Moroles), Mason Hewitt (Khylin Rhambo), Corey (Michael Johnston), Brett Talbot (Cody Saintgnue), 2 new boys, 1 new girl, Sydney (Claire Bryétt Andrew), Sheriff Stilinski (Linden Ashby), Melissa McCall (Melissa Ponzio), Jordan Parrish (Ryan Kelley), Mr. Garrett Douglas (Pete Ploszek), Etc will be staying in beacon Hills. They will all still cross paths and help eachother out. While Scott will be the Alpha of his pack and Liam of his pack.
Jake T. Austin, Ross Lynch and Halston Sage are rumored to make appearances in Season 6.