I'm hoping they'll leave her, or maybe just have her make very rare cameos like in ATF. I think Joss initially said no to bringing Cordelia back, but he liked what Brian Lynch did with her. I liked that use of her character, I think it worked well and I don't think it took anything away from "You're Welcome" being her last episode.
I wouldn't want her to come back properly though. She's a legitimate higher power now, working for good (and Angel from a far), that's a pretty perfect conclusion for me.
But as I've said before, had SMG been available, I highly doubt we would have seen Cordelia beyond her comatose body in "Home". Whether under those circumstances she might have woken up in the comics at some point... maybe.