As we've seen only straight Action cards, I really like to see one Victory and one Reaction card in this set (Both Alchemy and Cornucopia had a Victory card, Alchemy didn't have a Reaction, though). A Treasure Card would be nice, but not necessary for me (Both Alchemy and Cornucopia had one).
Then I think we will see 2 Attack cards, one Curser and maybe one that messes with the top of your opponents' decks (each set had at least one curser, Alchemy had 2 Attacks and Cornupia 3 Attacks).
We haven't seen any card with +Buy yet, maybe one Attack card will have +Buy, but I expect 2 cards to come with +Buy (Alchemy had one, Cornucopia had two).
Herald is a pseudo-village. But will there be a real village with +2 Actions? I guess, yes. (Cornucopia had even 2 villages, Alchemy had one and one pseudo village)
What else is missing?
No card which gains cards so far; Butcher doesn't count, I mean a Workshop variant, Alchemy had University and Cornucopia had Horn of Plenty.
Herald is kinda non-terminal draw, but as Cornucopia had Hunting Party and Alchemy had Alchemist, Apothecary and Scrying Pool we might see one.