If Aizen hurts Tatsuki, much like he intends to do, Orihime will most definitely have the will to hurt him. And Santen Kesshun would be the perfect tool. I suspect it's what she planned to use on the Hogyoku anyway. Ichigo will have to shut his mouth and realise that she's the key to his victory all along.
One of the reasons I support his pairing, is that Ichigo is seen to actively care for Orihime, in ways he doesn't do for anyone else. Even after he's seen her strength, he still tries to keep her out of harms way. The main reason he fights Grimmjow, despite the many claims he should have taken the girl and run, is because Grimmjow threatens her life.
Thanks to Ami for the sigs.
[I]"I am the vanguard of your destruction"[/I]- Sovereign, Mass Effect 1