Finally!
Spoiler for 263 manga and up:
Ichigo does not and never did = Kaien. That much is certain. And we can put that theory to rest because Kaien's alive and in the flesh, and and currently an extremely dorky espada with Dissociative Identity Disorder. Maybe Ichigo and him can compare notes on hollow suppression
.
That means Orihime is less likely to be Miyako, and that's why KT never pursued the theory. The man's a genius.