[2ndGoat]

My thoughts... without reading this whole thread.

1) I think people have considered this before under the label of "metagame." "It may generally be best to fold here, but if you've been folding a lot you need to call." That's a rough approximation of "You need to fold 80% of the time here."
2) I believe most serious computer simulations operate this way. My biggest compliment to the computer simulations I've studied (briefly) is their ability to mix up decisions and not do the same thing in the same situation every time.
3) My concern is that using this notation would lead to cop outs. Say there's is a {100,0,0] answer and we just can't deduce it, so we guess {70,30,0}. That's a lot different than {70,30,0} being correct because of game theory decision-balancing concerns.
4) This feels like moving from newtonian to quantum physics.

2nd