Having thought about this for a few hours, I am very curious to see how they plan to maintain the levels of asymmetric civ design they have heretofore promised but have not yet demonstrated.
Asymmetric civ design has been a fundamental expectation in the Age series since Age of Mythology and requires a healthy diet of unique units, unique buildings, and unique techs and cannot be achieved with a reliance on a unified roster of units and buildings.
We fans of AoM, AoEO, and AoE3 can attest to the development constraints imposed on good civ design. You can’t make amazing and unique civs and also balance 36 of them. There’s a natural tension between quality and quantity that cannot easily be solved.
As @anon63664082 aptly said, “The current limited asymmetric gameplay elements in Age of Empires IV, with exception to the Mongols, give the impression that they are gimmicks, different ways to do the exact same thing. They give a surface level impression of asymmetric civ design without actually making the game more interesting to play, like unique units and technologies would. Perhaps there is more to these asymmetric gameplay elements than I can perceive at this time. We shall see.” If true, this would be a return to higher a quantity of civs of lower quality. That’s an anathema to me (and many others here), but I understand it is business as usual to others who enjoy the earlier Age games.
I am deeply curious to see how the Devs rise to the challenge of making a second civ that must contain the apparently tentpole unique feature of the existing Delhi Sultanate – elephant units.
If the major feature so special about the Dehli Sultanate is simply repeated in a second civ, then that feature is no longer so special at all. Accordingly, if the Devs plan to continue to expand the game with more and more civs, they need to cram each civ with many different unique features in order for the new ones to not step on the toes and water down the existing ones.
This kind of nuanced and strategic civ design is what caused so many of us to fall in love with games like Age of Mythology and Age of Empires Online. I am fascinated to see if the new generation of Developers can follow in their footsteps.
However, those two games do not use unified unit rosters and also deviate significantly with unique buildings and technologies. Those games are designed to be expanded in amazing directions, but even then, there’s only so much you can do before you drift too far and lose cohesion among the roster of civs.