I have heard on both Fextralife and Wolfheart recaps of the private content creator preview that all companions can be fully reclassed.
Since this is optional, its completely up to you if Wyll, Gale, or Shadowhearts’ classes don’t match their stories. I think this is the right design choice. I won’t change any character with a class intrinsic to their background, but for players who don’t care about the dissonance, why not just give them that option? It isn’t costing anybody anything.
