Belichick has consistently shown an interest in bringing aging elite athletes in - once-great players that are looking for another shot.
Sometimes this has worked out: Junior Seau, Randy Moss, a bit of Rodney Harrison, Doug Flutie, & Corey Dillon.
Sometimes it hasn't: Torry Holt, Chad Ocho Cinco, Reggie Wayne, Joey Galloway, Joseph Addai, John Lynch, a bit of Tim Tebow. Others that don't come to mind.
So, empirically, the odds are against another Randy Moss phenomenon.
I agree, while the decision will be tough, there are enough roster spots in play to find someone to release:
RB Joey Iosefa - Pats have parted ways with RB's before after a single big game.
TE Asante Cleveland - good odds he makes the practice squad and Chandler may return soon. Four TE's is a luxury at this time of the season.
DT Ishmaa'ily Kitchen or Sealver Siliga - Brown, Hicks, Branch playing well; neither Kitchen nor Siliga in much of a rotation - 5 DT's is also a luxury.
LB/ST Jonathan Freeny/Jon Bostic/Darius Fleming - some concern with the lingering knee issue for Hightower, but they have six LB's and their defense often runs on two. As noted, Freeny could go to IR. Haven't seen anything special from Bostic or Fleming.
S Tavon Wilson - Seven safeties? They can make do with six, even with McCourty injured. Or IR Chung - which you hate to do - if it's remotely serious. Harmon, Richards, Ebner played a lot. Brandon King is the gunner. Lots of depth here.