So all the armies that got new models haven't really had a release of the new model, it was only a bundled product, with two exceptions, realm of chaos, karnack, the hounds, and the infernal enrapturess and fiends who both a larger expanded release when they're kits were sold outside of realm of chaos.
I think looking at that is a good indicator of what they will do in future especially how they did khorne, a box set with new kits followed by a release of new kits along with more new kits, only this time this release won't accompany a new battletome.
You also have all this staff and writers dedicated to battletomes, theyve been cranking them out at a crazy pace so once all the times are out they must have something they want to shift the writing staff to, maybe furthering the lore of the world in other ways than just battle times ala malign portents perhaps
This makes slot of business sense imo