I don't like the reasoning behind the idea that the game becomes dull after a certain era, which led them to the implementation of multiple civilization-switching mechanic. What I never understood is why they don't just create more content for every civilization. For example, the USA could have minutemen as an early unit, or some sort of stronger settler unit, and then progress with two more modern-era units, like cowboys and a contemporary jet. Additionally, they could be given three unique buildings, balanced in a way that nothing is overpowered compared to generic units, but still adds more flavor to the game.
Also, give ancient/classical civilizations something that fits them in the contemporary era. For example, Egypt could have a modern unit, like a 19th-century Muhammad Ali cavalry(they already mixed ancient and modern Persia in Civ 6 which are kind of completely different cultures compared), or Rome could have an Italian battleship literally named Roma, similar to Minas Gerais in Civ 6.
Balancing should be made in a way that units shouldn't be much stronger, but they could have its own tweaks and unique abilities that would be carried by later upgraded units, maybe legions could repair tiles and later melee units its upgrades into, while they could only build forts in Classical era, something like that.
I hope they will make some kind of scenario or patch that will give us a chance to play with only one civ, even if that is not main path of the game right now.
Anyway, I think huge window has been opened for any other competitor to enter and grab a big portion of Civ player base.
