Board Thread:General Discussion/@comment-10266932-20130531151056/@comment-27848649-20160222181357

Since Yhwach can control Ichigo (partially) via Blut Vein, it makes sense that Ichigo's Bankai is a combination of his Quincy and Hollow powers, something that Yhwach cannot control at all (Hollows being poisonous to Quincys). I also think that Ichigo's Zanpakuto is completely unique, in that his Inner Hollow is actually his Zanpakuto, unlike the Visoreds. We see that when Ichigo picks the Asauchi who will become his new Zanpakuto, it changes to resemble Hollow Ichigo, complete with a Hollow like mask.

Byakuya stated when fighting with Ichigo that he compresses all of the fighting ability of his Bankai into a small blade, rendering him crazy fast and strong. If this holds true with his new, split Zanpakuto, we might see Ichigo having both his swords in his Bankai state as well. I don't think that his swords will be identical in appearance. They might have the same form, i.e. two regular sized Zanpakuto, but different colors. Maybe black and white, representing the two sides of his powers.

Also, recall Ichigo's Hollow form when he defeated Ulquiorra. I think this was Ichigo's true form when in Bankai, not his Bankai's true form. This is why he was able to summon his sword telekinetically. Old Man Zangetsu himself states that all of the times that Ichigo almost died (or did die), it was his inner Hollow that saved him. Since his inner Hollow is his Zanpakuto, Ichigo's Hollow form should technically be his true form in Bankai, albeit one that he can fully control. Since getting his new Zanpakuto, his Bankai form should have him wearing a Hollow mask.

So to conclude, Ichigo should have all the abilities of a Hollow in his Bankai state (Cero, Instant Regeneration, maybe even Resurrección) along with two swords, and a mask. Ichigo will probably resemble Hollow Ichigo (except for the hair), white clothing and all. We might see some influence from his Fullbring in his appearance, but since most of his Fullbring powers were taken by Ginjo, the effect will likely be minimal.