Comme je le postais quelques pages plus tôt, direct from Gavin Norman :
As I mentioned in campaign description, and at various points in the comments thread: the Black Box and the Rules Tome are just the beginning of Old-School Essentials! We have lots of plans for more books in the Old-School Essentials line, bringing in new classes, equipment, spells, monsters, treasures, and rules options for different genres — all 100% compatible with the core game. Here are a few of the books that are in the works / in discussion:
Advanced Fantasy: Monsters: A selection of iconic monsters inspired by the Advanced rules from the 1970s, adapted to the Old-School Essentials rules.
Post-Apocalyptic Genre Rules: Road warrior style rules for wasteland exploration, souped up vehicles, and car combat. Includes 10 new character classes, 100% compatible with the Classic Fantasy classes.
Lost Worlds and Forbidden Temples: Dinosaurs, monsters from lands that time forgot, guardians of ruined temples, denizens of the deep jungle. A book of monsters to add a pulp Lost World element to your games!
Pact magic: Two types of playable character — the warlock and tiefling — whose power originates from pacts with planar entities.
Biological magic: Twisted secrets of bio-sorcery, genetic manipulation, vat-cloning, and flesh warping.
...and lots more to come!