One X factor to think about in the 2 faction scenario is how many people have complained that there is no Italian faction. I can envision a boycott of a 2nd DLC that did not include Italians.
Certainly something to consider.
Or perhaps the game's budget (relatively speaking, as I know the costs of development are only getting more bloated and expensive as time passes) just wasn't large to fully deliver on what was promised?
That's probably the case. The lackluster nature of the current "roadmaps" just made me wonder if it was originally where the release of OST and US was supposed to occur.