What I don't quite understand is, isn't there a chance that Zaraki might put shackles on himself again? He's going to lose eventually, and he's going to be even more bored now than before.
The manga will likely end at a point when we will never find out is he happens to shackle himself again or not. He fullfiller his dream at last, so he might change his behaviour too. I'm waiting for his and Yachirus interaction after he get's out of there to see how she reacts to his change.
That's what I wondered. It's not like the shackles were a deliberate thing, it was subconscious. So what's to stop him falling into the same pit again? I guess he's not a child any more, so his current level of ...'maturity' (because he's not really that mature) could stop him. Also, he's already defeated Unohana. Keeping her around was the reason his young self started holding back. Now she's gone, he has no reason to, on a psychological level.
But he's going to be even more bored than ever now, I think, now that he's tasted 'true battle' for the first time.
Maybe he'll resort to wearing two eyepatches, one on each eye, lol. Or a reiatsu-draining gimp mask . There's an image.
Well, perhaps being able to communicate with his zampakuto will make a difference in regards to kenpachi shackling himself again. Perhaps ichigo is no longer a good point of reference as to how shinigami powers work however it is worth noting that the amount of power ichigo could release and control did depend on ichigo's connection and relation to zangetsu. If other shinigami are even vaguely similar then perhaps just being able to communicate with his zampakuto will be a more effective way to control his own power. Kenpachi's zampakuto is arguably powerful so perhaps kenpachi can keep himself in top shape by fighting him though...