Peace, Kinsler and Phillips are all free agents after this season. Maybe the Sox bring back Pearce, whose career has largely been as a bench player. I suppose they might bring back Phillips, but despite of his MiLB deal this year, has a long history of being very picky about his contracts and where he plays.
3B is easily wide open for Devers, unless the Sox bring in someone like Moustakas or Donaldson (which isn't likely). Moreland likely has 1B, although at his salary a bench role is hardly unprecedented.
As for catcher, that is one position the Sox have an abundance of at the major league level. All3 backstops are under contract for next season, and of the three, Swihart is probably the most tradeable for reasons related to age/potential, salary, control and versatility. Sure, you can move, say, Leon, but takers won't be begging for him as opposed to what can be had on cheap deals or in cheap trades. If the goal is to get a catcher who excels both offensively and defensively, don't hold your breath...