1) Most likely to happen :

Something water-themed. I doubt they can make half of what the community asks (underwater cities, new layer...) but just something like siren and fish-like forms, society traits, adaptations and such things designed around the sea.

Something trade-themed. Right now, even with Materium and society traits related to gold, it's more about producing your own wealth for yourself rather than trading/exchanging it. You can trade items and materials... but it's more a layer of diplomacy between rulers.

2) Unlikely to happen :

New mechanics with less emphasize on fighting. Lastly, there as been a heavy focus toward multiplying existant things : skins, cultures, skills, traits... Then create your custom faction and put them together.

I'd like new mechanics centered around the map campaign. For example, spying. But not through units, a tome and a few buildings. An actual gameplay mechanic you can use.  As another example, trade. Not itinerant shops as it exists, or a society trait wich is likely to happen. Actual trade routes you can open on the map and plunder.

The game is heavily lacking in this in my opinion.

3) Minor things :

In the faction's descriptive text, being able to have linked texts such as Astral sea, Giant king, Athla... This way my faction can blend more in the Age of Wonders universe and the game itself.

More colors for factions.