Re: After Warhammer
You are overestimating the number of teams, the supposed simultaneous existence of a historical and a fantasy team is just a marketing slogan, but with little basis on reality. I remember people seriously believing that the next historical title (following Attila) was going to be released in late 2017. They even mistook the teaser for Warhammer II (lizzard pyramids) for a subtle reference to the Spanish conquest of Mexico. In reality, Three Kingdoms was released 4 years after Attila and Warhammer III exactly 4 years (what a coincidence, it's almost if there's a pattern!) after Warhammer II, despite the alleged coexistence of multiple teams...
Best case scenario, historical and fantasy teams technically coexist, in the sense that, right now, there is a handful of guys brainstorming over the next title. More likely, in certain years (like 2016), the historical team was complete fantasy and nobody worked on anything. The alleged existence of multiple teams is just a PR excuse to placate the fans that may not appreciate the current trend (fantasy ones in 2018/2019 and historical ones in 2015-2017). Darren (a former employee of Creative Assembly) had talked about the tactic of dropping an unverifiable and completely misleading statement, which functions like ammunition for censoring criticism. I believe his example was about how the AI was supposed to excel in the simplified city layouts in Warhammer, which the fans naively swallowed it, despite being complete bullocks. But it's a very common practice, I also remember that Attila was planned for future graphics cards and was definitely not just poorly optimised...
Anyway, multiple teams of significant size are unbelievable, because that would mean an unnecessary increase in expenses, especially since productivity has not grown proportionately. My guess is that right now the vast majority of CA's staff is busy with Warhammer III, with a few being dedicated to lord packs for Warhammer II and Three Kingdoms. Once Warhammer III is released, the divide will be between the DLC team for Warhammer III, a small number of people focused on Three Kingdoms and the majority being dedicated to the next tent-pole title (to be released in 2023), historical or fatnasy. The current trend points towards the latter. This estimation is not pure speculation. A CA employee accidentally revealed in the official forums that they refer to Troy as the "historical prject" to differentiate it from the rest of their products, meaning that no historical game is actually on the works.