I dont see why people emphasize on the "only 1 faction part". Why does there have to be same amount of factions on each side. As of right now we know that germans have the late game advantage, due to their known firepower. Allies will have diversity with the Brits.
Also, the two remaining factions will just get more commanders, abillities and units, and thus make them more versatile.
I am lucky just to see 1 faction, for all we know they could just have stopped working on CoH2 after WFA