Devers can either stay at 3B or move to another LF/1B (if he hits the milestones expected). Nobody significant is blocking any of those spots.
Moncada is likely to go to a corner too. He is playing 2B which makes sense, but given his size and age - he is probably going to outgrow it.
In terms of guys who could be dealt?
Swihart - you'd have to get something really good for the deal he's in. (like a #2/#3 pitcher with at least another year of control) His star has not been dimmed. He has burned two of his options, so the Sox will have to make decision on him one way or the other.
Somebody named Travis - you could go either way on this. There is no doubt that Shaw is a legitimate starter. But Travis could be ready for the bigs by the end of this year, and Ramirez could probably handle 3B. One again, this assumes there is a deal which makes sense to move Shaw. Travis has his own potential as a high on-base 15 HR Dave Magadan sort of guy ... that is a solid starter as well.
Jackie Bradley - he has done a lot to rehabilitate his stock. A quality center fielder who is cheap and controlled has innate value, especially since he seems to look like he can hit. Now offensively he is a baby Mike Napoli, the hot streaks can be great and the slumps can be deadly but the on base skills should play. But really, if Moncada is the real thing, Betts at CF and Moncada in RF makes a ton of sense.
Deven Merrero - a vacuum cleaner middle if who can hit enough to play. Not a centerpiece, but a very useful trade enhancer.