In Hearts of Iron III, when you're creating a new division and you're putting units into it, what you'll find is that, depending on you put in (say 2 inf units, a tank unit, and arty unit and an engineer unit) you'll receive a "combined arms" bonus. I wonder if CoH2 should do the same.
So, as you have more and different units in your army. (let's say an engi squad, 3-4 squads of infantry, an MG or 2, a mortar and a tank or two, based on what you have, your "combined arms" bonus will go up. For the sake of argument, it'll give all your units extra HP and speed (say)by up to 15 - 20%. Or perhaps it could be in proportion to your opponent's combined arms bonus as well.
So let's say your opponent is blobbing and has no combined arms bonus, you'll receive the full 20% bonuses, but if he's as combined arms orientated as you, your bonus would be much less (if any at all).
I think that this is not a good idea. If both players build versatile armies and one loses a unit, he is suddenly punished in two ways: losing his unit and losing (at least a part) of the bonus.
But the idea of reducing cover for 3+ squads on a spot sounds nice, as even small arms fire would be more punishing.