I really would be shocked if Pierce is bought out (by the C's). He just is too good and too productive a player, and his contract is too friendly. He has to have a decent amount of value, either to help a team shed payroll, or to help a team make a run next year.
The only way he would be bought out IMO is if it is as a favor to him, so he can choose his next destination. But, I don't think Danny will do that. I think Danny will work with him to find a situation that works for him, but he won't give away the asset for nothing. It is not Danny's MO.