1) Anti-blob mechanics like negative zeal that will increase hits/suppression on blobbed units.
I agree with your post, but you would need to implement a quite a radical redesign to the came for this to be in:
1. Change all the maps to be much more open, unit's typically don't have a lot of room to move around so they are stuck in a "blob" formation regardless of if you wish them to or not.
2. USF and Soviets need radical changes: Both have numerous weak infantry to make up for a lack of concentration in force. USF especially suffers from this as it gets nothing better than riflemen unless you go air borne, so to match an Axis players more concentrated fire power you need to group your units up.
3. Having more units than another person isn't blobbing. A lot of people give me shit because I keep my units together; that's because I don't like splitting them up by themselves because of how weak single squads are by themselves if the enemy decides to group their units. Keeping your units together in one army or spreading them out is a tactical decision, it's just that in the current meta you get more reward for having 1 or 2 big armies instead of units dispersed all across the map.