Maybe we could see a Ezmerelda d'Avenir's Libris Mortis.
I think a book about feys or aberrations would be more interesting than about giants.
If they want to publish a new Vecna's Book of Vile Darkness I doubt we saw a previous UA article, but maybe about a recovered PC: the hellbred from Fiendish Codex, and infernal dragonborn (styx, howling, pyroclastic, rust, Tarterian, gloom, chole and deathmask) + abyssal genasies (caustic, cinder, plague and void). But I don't advice to publish it in this year, because there is a lot of troubles, and let's say this type of horror will be not in the top of the wave for a time.
I like the idea of a new "transitive" plane ruled by giants and (elemental) titans, for example the "Thorn Hedge", the evil brother of the Faewild. That as a new setting would be easier to be sold.