With AoE 3’s resurgence, I think it’s time to also add some new features the other entries already had. And one feature that comes to mind in MP is Quick Play / Unranked matchmaking.
Using AoE 4 as an example, the game allows you to play unranked 1v1s and TGs in all sizes on top of offering Empire Wars as well as Nomad.
It also has a FFA queue for the Dominion win condition, which is a bit like Regicide.
Translated to AoE 3, you could add a FFA queue for Unknown. The map would fit perfectly for these condition due to all the randomness it offers.