My quiet wish for new PDX game (which probably won't ever happen) is late Rome into dark ages. Gameplay focusing on migration and then establishment of new kingdom for Germanic tribes. Challenge mode to keep Western Rome alive. Some eeirder alt history possibilities for Roman remnants holding out (Britain for example). Eastern Rome and Persia butting heads. Development of Christianity. Possibly rise of Islam to shake up the endgame.
They could build on the army and building based country systems from EU5 to model interaction between Western Rome and German tribes. Like a province is not controlled by a single country but there is this tug of war between tribal autonomy and Roman control where Rome can get soldiers from tribals in exchange for concessions to their leaders.
I'm not a big fan of Total War series, but I really liked the feel of the old world going to shit in TW:Attila
Don't know about Vic3 but PDX does have a lot of pop culture references in their game achievements:
The Freest Man in the World EU4
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Stardust Crusaders EU4
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Somehow He Has Returned HOI4:
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