First, no, it won't scale like that.

Second, don't forget that you're trading one complexity for another. Eliminate a drive shaft and you still have to get power to the wheel somehow, which means now you're running high power electrical cable in a very dynamic environment with exposure to the elements. On top of that, you need to cool the electric motor, so you're probably running some kind of fluid out to it. Not that it isn't a solvable problem, but it probably doesn't reduce the weight much, if at all, when the system is all added up. You'll find that while you eliminate an axle, you still need to mechanically connect the two wheels together (look at the rear subframe on an FWD car) for strength, which also reduces the weight loss. Then the steering on the front... etc.

Until a more significant change than this motor (where maybe a 2.8lb motor could produce 100hp without needing active cooling), we're better off with "inboard" motors still.