Agreed, with passion. We should not see Susan again, except in memories, or maybe if Harry is looking across time or something. Or, just possibly, if Harry ends up paying another visit to wherever it is that Colin is at, but even then, probably not. Though I won't be surprised if we do see Carmichael and Colin again, in some form. But I hope not restored to Earthly life.
I third this, though it'd be super painful to Harry (and thus entertaining) if she was alive in Mirror, Mirror, and human, but hated Harry with a passion for who MirrorHarry had become.
I was thinking even prior to the attack that she looked a little drained.
My interpretation is a bit simple: she was inside Harry for a long, long time. I got the sense that Shadows were not built for long-term use; they're about as disposable as a Glade Plug-in (I'm partial to the apple scents myself). It's like a piece of machinery that was running nonstop for a decade; eventually, it just starts to break down.
That, and let's face it: she's as beat up emotionally as Harry was over the previous few years. That's gotta take a toll, Fallen or not.
Anyway, all of this is to say that I don't see that as significant in any way other than showing... depreciation of an asset, in cold terms. Still, it's a good observation.
