Upgrade sprues for Freeguild, Disspossessed, Ironweld Arsenal, etc., or City-themed (with an heraldic book ? Like Firestorm 2.0) would be awesome, and would come along nicely with reboxing (like the new Blood / Dark Angels Primaris kit + sprue).
Some new heroes sculpts*, some upgrade sprues, round bases, new paint schemes and there you have it: an AOS themed armies** without too much efforts !
*Like the ones coming in WHQ : Silver tower. (BTW I read somewhere, DakkaDakka (?) some speculation (!) about a new Death themed Warhammer quest, "Black Pyramid", that would be awesome too, also a way to add diversity and new heroes to the Death range, oh well, one can dream ...).
**I really hope the Cubicle7 AOS RPG will bring such details to the Mortal Realms. I am really looking forward to it (and to the WFB one too ofc !)
Excellent post Rogue Explorator ! I would love to see 2018 going that way. The Malign Portents "banner" could totally be Deathrattle related too, and the "re imagination" of catapults, etc. would be a good way to mix "low" and "high fantasy" esthetics ! As for the second faction you imagine, don't forget the "Reanimant" keyword, only present in Morghasts and all the Tomb King constructs : GW surely has to do something with it...
ANYWAY, I wish December would go faster ; as soon as the ETB Nurgle and Primaris and the Lord Celestant (16/23 dec) are out, I'm sure GW will start teasing Malign Portents and Nurgle properly Good times ahead !