I think the main problem would be they like to start at two factions then expand to four. So you'd either have like, Ita vs Commonwealth, which wouldn't have Germans and is therefore illegal according to Relic, or Germany vs France, which may be underwhelming because a lot of people don't like France or think they have a really bad military reputation / no interesting units.
But boy it would be a breath of fresh air. North Africa campaign, Fall Gelb campaign.
Could even do a '41 era Soviets thing but I can't think of a third faction to add unless it's... ostheer... again. God I'm sick of two Germ factions every game
(