Come to think of it... I think someone made a good point
To avoid another NA scenario of a long wait and a theater of war that doesn't appeal to all, I would say:
Ardenne alongside a specific theater of war... say, Early war, Russia or Pacific
Italian campaign alongside another new theater.... etc, etc
Why?
Because italy requires addition of more stuff, same as Ardenne. these can be grown into and don't require a complete focus to achieve... However, new theaters do, and to have one and the other is to avoid the NA phenomenon. But hey, that's just my thinking.. This eint the Suggestion section