Doesn't matter who wins between Catalans and Huddersfield, because Saints will choose them, and I can't see either getting one over Saints at Langtree Park.
There's an outside chance Castleford could have a last gasp win over Wire at their place, but unlikely given form. So that sets up a Wigan v Wire semi. With Warrington's form very patchy, and now without Russell at fullback, I'd see Wigan winning that one.
So Saints v Wigan at Old Trafford, and possibly the most one-sided final ever.