We know from the stuff people have datamined as well as other BG3 related material such as the MtG promotional cards that there's at least 3 more companions in the game, all of whom are extremely likely to be good aligned with what we know about them. One in particular is 100% a good aligned character that will be suitable for any good party. Even if you don't consider Gale or Wyll to be suitable for good parties (even though they are very clearly good aligned or at least neutral), you'll very likely to be able still make a full party of good aligned characters with these 3 additional party members.
Assuming you are right (which I am not convinced of), there is still the question of whether those three will each uniquely fill one of those four classic D&D party roles? If that criterion is also amazingly satisfied by those three companions, that still leaves me with only being able to play, as my PC, that one party role left uncovered by those three companions. So, for example, if those three "good" companions are damage dealer, controller, and healer, then the best scenario I get from BG3 is that I must always play a tank PC.
