The only reason we are not all riding electric motocross bikes yet is because the technology isn't there yet. The logistics of running and charging electric bikes are the limiting factor, not the fact that people would miss the noise (although I'm sure a few will!).
There are electric off road bikes being developed and they are starting to be seen in places but bang for buck it's not quite there yet.
I personally believe brushless buggies are the future whatever the scale. They are clean, easy to maintain and easy to understand. You don't 'need' 2 x 8000mah packs to make em run, these guys are extreme examples but you do need more volts than on 10th scale.
Jonathan - I would like to be the first to order an S8 please mate
