And then I had a full-on Ratatouille flashback to this 2D physics app I used to have on OS 9 called Interactive Physics. I used to have so much fun with that damn app. John Knoll was a fan as well and actually found a way to use motion from it in his ElectricImage animations. A classmate of mine actually created short films using it back in the early '90s when computers were beige. Funny, funny films of bad things happening to little stick figure guys.
So now that a badass 2D physics solver is just sitting there on the interwebs, free for the porting, some enterprising AE genius simply must write a script to animate 2D AE shape and solid layers this way. You'd be a hero to the AE community. Your PayPal donations button would receive literally several clicks. You'd be a man among kings.
C'mon. Do it.