I played in WarBirds for years. When they opened up the Armored Assault arena it catered to a smaller crowd and only had two countries.
I often had to fight against up to 10 to 1 odds because players in a certain squad ( I will not mention by name ) would not change countries
to balance the sides. In time I got better and took them on and did fairly well using stealth, surprise, and good aim from lots and lots of practice offline.
In the case of Aces High, three sides is a the better road for a combat sim. If you are getting horded by one country and cannot compete, then you re-spawn from another base or attack the other country. The 3 sides have fairly similar terrains and are balanced almost perfectly by their terrain builder. A 2 country sim could require all of the maps to be redone. That is not cost effective. I anticipate AH numbers will come back up. Allot of $$$ has been invested to upgrade to AH3. Many players are going back to the PC for internet gaming. AH will come back.
Armored Assault vs. Main. Different animals. Warbirds rarely had side balance issues. Certainly not to the extent we do.
The other day we had 18 Bishops fighting 17 Rooks while four Knights twiddled thumbs. Can't tell you how many players logged in said nah and left. Had they stayed and not been forced to be stuck on a side they might have stayed. Two sides they certainly would have.