SEGA's long running strategy of supporting Total War games with DLC remains unchanged, especially now that Creative Assembly is much bigger than it used to be. Aside from the main historical and Saga spin-off teams, they also have people constantly working on the fantasy series.
On a blog post, the folks at CA detailed what Total War: Warhammer II's DLC release schedule will be like in the foreseeable future.
Aside from the Reprisal Update which is already on beta and adds the Foundation Update changes from Warhammer I to Mortal Empires, the Old World map will also see Wulfrik, Throgg, and the Norscans raiding the south coasts soon. The 30th Anniversary Regiments of Renown will also be brought to the sequel, and the devs are exploring the possibility of giving all Old World Legendary Lords their own unique start positions.
While this might sound small and solely focused on the Mortal Empires campaign, it should be noted that Creative Assembly plays their cards pretty close to their chest -- we rarely get information about any update until a few weeks before it is due to be released, so don't take this for a complete roadmap in any way. If you want more content but can't wait for the official updates, check out our mods page for Total War: Warhammer II.