I remember seeing some speculation in the Reddit thread where one of the devs came in to assuage concerns and play PRball that CA was waiting until after the usual end of financial quarter/investor meeting before making some announcements, so it's interesting to see the trailer and news of Immortal Empires being made available to everyone a week following that. No idea if it's true or anything, but interesting. I think moving IE over is a good decision, because god knows the campaign mode in 3 was lambasted to hell and back. People just want IE. Hopefully the big DLC release in April throws in chaos stunties and a big bunch of bugfixes/balance tweaks, since the most recent update wasn't all that much.
I only know the bare minimum about AoS, but this series (and Vermintide) got me into the Warhammer Fantasy IP and now I really enjoy it. I even found a couple of the Gotrek & Felix books at my library and read through them. So maybe a Total War: AoS would be a neat way to introduce people to that setting. I feel like going for 40k would be the more obvious financial slam-dunk, though it has its own issues of translating that into a Total War game. Hell, I'd like to see them go totally nuts and make Warhammer: Total Warrior, just to see what could happen. It would probably still do better than whatever shit Jackals is going to end up as.