i'm not pressing the spoiler tag just yet. But I kinda doubt that they'll change a main protagonist's primary weapon between games. Assuming that Patroklos will still be the main protagonist, that is.Or the more likely scenario (and what will probably happen) is that next game Pat will just use battoujutsu with some of his vanilla moves thrown in.
If you play Story Mode, it clearly states that:The battoujutsu Setsuka taught him IS his original fighting style. He used Alexandra stuff later on after learning about how his mother fought, to try and emulate her. Original Pat is basically a front, a false persona that Siegfried and Z.W.E.I. literally beat out of him and teach him to be true to himself. After he does that he uses his real style, the battoujutsu Setsuka taught him, and kicks Z.W.E.I.'s ass.