While talking to EW, Ferrell said “Yes, I’m taking over,” He goes on to say “My character’s name is Deangelo Vickers, he loves the American Southwest, and he’s just kind of in his own way going to step into Michael Scott’s shoes and try to fill them. I’m friends with Steve and a fan of the show, and I just selfishly wanted to do one episode with him, and they pitched multiple ones, and I said, ‘That’d be great.’”
It is already widely known that Will Ferrell will be guest starring in four episodes this season, but he wasn't due to appear in the last couple of episodes including the season finale. Might he still take over for Steve Carell full time next season? ”Yeah,” replied Ferrell. “A regular, full-time gig." EW is also reporting that a source close to Ferrell has stated that Will Ferrell's schedule is being cleared at the moment to accommodate doing the show.
Chances are good that Will Ferrell was just teasing the reporter a bit. Ferrell is well known for his unique sense of humor. Rainn Wilson (Dwight) seems to think Ferrell joining the cast is unlikely. He goes on to say: “Will is coming in as a possible boss but everyone knows he is not going to stay because he makes $20 million a film, he’s got other fish to fry.”
Regardless if Will Ferrell or Will Arnett are picked to take over Michael Scott's job, I'm sure either one will do a great job. It's still very possible that neither Ferrell or Arnett will be picked to take over. I will report more as soon as I know. Thank you for your time and for your support, it means a lot to me!