I think Pariahs will be able to find a home as Lychguard, for some. Lychguard are the CC unit with warscythes as standard weapons, I believe...and that's what Pariahs were (or were supposed to be) in the old codex.
I'm kind of disheartened by the things I've heard recently about Wraiths and Destroyers...though, actually, I've never really liked the Destroyer model, so maybe it's a blessing in disguise (for me). Of course I'm really eager to see the book and figure out what's really going on for myself.