Ayon *should* put up a challenge. Come on Kubo, whats the harm of having Appaci, Rose, and Sung-Sun have a shining moment that doesn't end with total humiliation? For Tia's sake, just give it to 'em. Besides, its not like Ichigo has to end EVERY battle by going Bankai. I'm actually rather enjoying the fact that our main protagonist is holding his own in shikai (against Kirge's Vollstandig) while remaining relatively unscathed. So if someone else should defeat Kirge and allow Ichigo to quit while he's ahead, I don't think I'd mind too much.
But realistically speaking, I'm thinking Kirge's probably going to find some way to reduce Ayon to spirit particles and collect that energy. That will be what pushes Ichigo to go Bankai. I hope I'm way off though.