i dont think its feasible to put a "retina display" in i pad 3. such a high quality display on a 10 inch screen is surely bound to affect the incredible battery performance? i think so...
more powerful battery in such a case...and if apple succeeds in giving us a retina display and improved battery life will the price remain same?
personally i think the i pad 2 display is good enough but i havent used an i phone though .
i just think it will be an incremental upgrade just as in the case of i phone 4s...