Levistus's_Leviathan
5e Freelancer
Looks like I was wrong with the Spring release. Hopefully it comes out later this year (preferably in Q2).Spring: Someone's Guide/Tome to/of Dragons (Draconomicon including the Dragon subclasses from the most recent UA)
Summer: Ravenloft or Innistrad Setting Book (based on the Undead Warlock/Spirits Bard UA)
Late Summer/Fall: Adventure book/books, probably taking place in Neverwinter or Anauroch.
Fall: Planescape/Compendium of the Planes???
Edit: Maybe they're doing 5 books this year? It's unlikely, but not impossible. They've done it before.