I could be wrong but im positive that basic sith classes dont exsist in the Star Wars RolePlaying Game made by wizards of the coast (which this game is based off). There is only Guardians and Cosulars in there (yeah, no sentinal, thats a bioware creation). So while its possible they would have to build the new base classes from scratch, and even if they did the differance between them and the starting jedi classes would be so similiar that it wouldnt be worth it IMO.