Will Ferrell will replace Steve Carell as the boss at Dunder Mifflin in the next few episodes of "The Office", and NBC has given the first taste of his appearance. In a newly released sneak peek, the successor and Michael Scott are seen sharing a big hug. Carell's departure story arc starts as his character Scott proposed to Holly Flax in the March 24 episode. It was also revealed that he will follow her to Colorado. After this heart-warming episode, "The Office" goes on a hiatus before returning on April 14 with the first of a multi-episode arc by Ferrell.
Although Ferrell is the replacement, NBC has stated he would not be a full-time cast. His multi-episode arc indeed will end a week after Carell leaves the show on April 28.
source: aceshowbiz