Wouldn't the nitrous system take too much space judging by the electric motor and all the fancy stuff the car will have in order to have all this power? Nitrous is fine as a stand-alone accessory for nitrous but we're talking about an ESC, Motor, Battery, The receiver battery going to another...
It's a tough job to do, but it's all a fantasy we all crave for the performance of a recovery motor like you say KERS. I've been dreaming about this for years
I've also had this idea for my T-Maxx 3.3, but there might be a way around it, instead of the pinion on the motor being locked on, we use a centrifugal clutch for the motor, only the motor engages when the nitro engine is at redline for improve speeds, then a servo will control how much power...