Yes, lot of people want Vikings, Byzantines, Japanese, Spanish…
But I mean:
What kind of features and mechanics - what would You You like to see?
For Example , we have cavalry focused French with economical bonuses, Infatry focused HRE with prelats, who inspire villagers
a sea trade nation would be fine like venetia
A civ that gets points for killing enemy units and can spend them on unit buffs or something. Like a sort of morale system.
Maybe a civ that has 3 landmark choices instead of 2.
The Magister Militum should be atleast as powerful as an Early Knight, so while It’s powerful it can also be a double edge sword, targeted and killed early on if not careful.
As the Aztecs maybe?
Aztecs: I even do a possible civ bonus for them, although I’m still not encouraged enough to release a full Aztec version, but more or less it would go like this:
Sacrificial Rituals: Melee units are able to “Capture” enemies instead of killing them. Captured enemies do not leave a corpse. Prisoners must be brought to a building, the sacrificial arena as if it were a resource (or automatically, for balancing reasons). The number of prisoners can be traded to perform rituals (similar to the Mali with the Grand Bazaar and the Age3 mechanic of native rituals):
Since I don’t have a clear definition of the lesser gods of the Aztecs, and which ones they worshiped or which were just part of polytheistic folklore, I’ll leave it there, I still have to read more to come up with more rituals. With the Incas if I have it clearer, although…
Incas: In the case of the Incas, I still haven’t decided between 3 bonuses:
-Agricultural civilization, which gives economic boosts based on the amount of food currently stored, 1000 gives a 10% bonus, 2000 - 20%, 5000 - 30%, similar to the Russian hunting bonus or representing the city Baghdad circular with the Abbasids.
-Dynasties: Then there is a dynasty mechanic, similar to the Chinese, with the 4th age dynasty (Vilcabamba) unlocking cannons and arquebusiers.
-Agricultural rituals: The third mechanic is that of rituals, although it can go hand in hand with that of dynasties or the first, you practically sacrifice food to improve the economic, siege or attack bonuses of your units. The Incas sacrificed food, vegetables or animals at their parties, and they drank a lot. Only in case of droughts, famines and wars, did they make human sacrifices, so sacrificing them can be ignored.
Japanese , Vikings and Byzantines of course !!! most playable civs in last aoe… or maybe my most playable 
Ha - my exact wishlist for new civs too!
Adding some naval civilizations would most certainly be a good idea and examples of naval civs include the Chola Dynasty, Japanese, Koreans, Mayapahit Empire, and Venetians.
Guys, I wanted to open discuson about future civilisation mechanics and features, not about civilisations themself - there are many discussions about this already…
So I changed the topic name a bit
Yes, I though about "Rise of ############# " DLC with Mayapahit Empire and Venetians as new civilisations, new special water maps with special naval mechanics etc
My only issue with “water civs” is I think that all civs need to be good on water maps.
This is a problem that AoE2 has where only a small subset of civs are even viable on water maps. So those are the only ones that get played.
So civs can have unique water things for sure, maybe even stronger late game advantages, but they all need to be able to compete for water control.
Ha only took a few comments before your point was totally ignored 
I would like to see mechanic for certain civilisations, where civilisation collects “5th resource” (name is not important) in combat. Similar to Age of Mythology’s Favor.
For example Vikings could earn “5th resource” in “5th resource” in combat, Venetians or majapahit in sea trade.
this “5th resource” can be spend on extra units, temporary economical bufs , or maybe unique technology
BTW, this is field, where I see big potential for AoE4
110% agree,
This is very important point, I would like to have “water civs” , but if these “water civs” would be overpowered on water maps, it would be pointless to play with other civs, and that would breake the game
I think, that I wrote the topic’s name wrong, hopefully, I will navigate it back…