i think he'll follow in his father footstep and use two sword, but I can see a case for the other options.
One-sword style because he has ame no habakiri and decided to use only it.
Two-sword style if enma is returned (highly unlikely, it'll forever haunt seth-chan)

but he can use other swords as a replacement.
Three-sword style if he gets taught by zoro in eos when Zoro is making babies with hiyori.
