I hope they make another faction.
Some will oppose this, but I just really like how Relic give their armies "character" - voice acting, models, gameplay, each army feels unique, it's awesome!
I could imagine Italians. As part of an Afrika Korps-styled army.
Or, the addition of desert maps without a new faction, BUT with new uniforms for the existing factions (even though it could be
extremly weird to see soviets in the sand)
I also always wanted to see a 2nd Soviet faction, sth that is what OKW is to Ostheer, just for the russians/soviets. It could be some sort of Guards Army; and it could - just like OKW did for "Germany fans" - serve the more frequent requests of "Soviet fans", e.g. by including real frontline troops (sth like "Strelky"), stock T34/85s (maybe with red banner to make them distinct) etc. It could also elaborate the "themes" of the soviet army even more; just like OKW expanded upon the whole elite, heavy theme Ostheer had initially. Such themes could include an ideological factor (flags'n stuff), women's participation in the Red Army (maybe as some stationary weapon crews; seizing this opportunity, Relic could finally fix some of the female weapon crew animations [the reason female partisans were removed]) etc. etc.
At the same time it would provide the normal, less-trashy-themed (conscripts) frontline soldier for the Red Army (as I said, "Strelky" or sth. like that); just like okw gave the germans their much desired field grey-uniformed frontline dudes, this faction would give the "russia fans" what they want.
^^Sry, got carried away abit

But there is just so many more interesting things they could explore in this cinematic ww2 setting!