Dual Blade, ok... kinda awesome. But I still feel his bankai will stay relatively the same, but this new arc will allow him to use his hollow powers again, so his power "phases" will be sealed>shikai>hollowified shikai>bankai>hollowified bankai>new power. Keeping with his old powerups, and not making the power up so out of left field.
There is no way Kubo would let ichigo's hollow powers just rot after there was so much done with them, all the way until the final getsuga. It's about time they came back.