I myself asked him to do something on the Zulu Wars. I think that would be quite the interesting challenge both for a game engine and the player.
At any rate here is the post as well as a link to the support form:
Both Kharkov '43 and Modern War have been huge successes for us and we are really looking forward to all the new games we want to do this year. I'd like to take an informal survey of the games you would most like to see, so when you get a chance, send a message to Support and let us know what games you are most interested in, either in our existing series or any new ideas you would like to see developed.