We made runtime on 2000 mAh cells back in the day with less efficient motors. We can do it again, it would start a little bit of a battery war in mod. A runtime war in mod might actually benefit the stock and superstock classes because it would push the battery development along.
I still think single cell is the way to go and it's starting to look like it will catch on. Several things will need to happen before it can become a ROAR/IFMAR change but it's a start.