I think the only sure field players for the Sox in 2018 are:
Beni
Betts
Vaz
Devers
Pedey
Rameriz (wish this wasn't true but who will take him with the $22.7 Mil salary)
The only clear FA pickup field player at this point would be Nunez. He was making 4,200,000 but will command a lot more now)
The players that might be used in trades would be JBJ, Bogaerts and Leon. JBJ's defense would be hard to replace.
So in my view, we might see a need for a 1st baseman, a SS and a backup catcher. Less likely, a need for a CF replacement.
We have Lin, Hernandez and Travis as possible utility players in 2018, with Holt, Moreland and Young likely gone from the roster.