There's very limited info so far, but there is this:

In the Age of Wonders 4: Primal Fury content pack, players will discover new ways to conquer the realms, and bring the land itself under their control. The new Primal Culture will enable rulers to channel an animal spirit that shapes their empire, both physically and spiritually. The Tome of Fey Mists and the Tome of the Stormborne, both added in Primal Fury, include new spells to conceal troops in magical fog, gain advantages over seas and shorelines, and even transform armies into fearsome nagas. The pack will also launch alongside the free Wolf Update, which will add new features and improvements requested by the Age of Wonders community, including a rework of necromancy, new randomly generated items, and War Bounties to better direct allies in conflicts.

Tentatively excited. I got both existing packs, and the sheer variety makes the game better, even if they're - IMO - overpriced for the content. Which is fair-ish, the base game has a lot for the money asked.

In any case, after the rather tepid Planetfall I'm happy they seem to have found their bearings with 4 again!