While this is a great idea that will eventually turn to become reality, once the materials, technology etc improve, as well as weight, I just wonder: why is this system based on the MLG? Would it not be as efficient to place it on the Nose Gear instead? There would be much less conversion costs on existing aircraft and most pushbacks and towings are done from the Nose Gear. Of course on a slippery or contaminated surface it would be less than ideal, so there might be cases where engines will have to run anyway.
Maybe this perspective has been looked at before?
Flex