The ringer has a lengthy discussion on players that could be traded or bought out this season that could be of interest to some.
https://www.theringer.com/nba/2018/12/17/18144188/nba-trade-season-primer
Some of the names mentioned as interesting expiring deals include
Enes Kanter
Jeremy Lin
Alec Burks
Dewayne Dedmon
KCP
Faried
Jr Smith
Demarre Carroll
Corey Joseph
Darren Collison
Wes Matthews
Anyone that we would want? In general there is a belief that this may not be a big moving trade deadline...
The problem is the Celts don't have cap space or any significant contracts to use to match salary.
The easiest to move contract for trade purposes is probably Morris as an expiring for about $5 million, but he's been pretty important to the team's success so far.
Other than that the guys you'd look to trade are all on lower cost deals.
Some of those names could be useful if they're bought out e.g. Lin, Kanter, Dedmon, Matthews, but that seems unlikely.
I could see Burks or J.R. getting bought out. Do we want J.R. Smith on this team?