Nick Carfardo is reporting that it will be a player who is currently on the 40-man roster:
Abe Alvarez, Kason Gabbard, David Pauley, Jermaine Van Buren, Alejandro Machado, Brandon Moss, Adam Stern
Along with what you said, the prospects the Sox probably wouldnt mind giving up
--------------------------------------------
EDIT: Jeez I didnt expect this soon to be trade, to be one of the biggest sport stories of the day