I personally think it could be a great alternative to cars and bikes for those who need to take a whole family somewhere or a decent amount of stuff.
Only modifications I would make would be ride-by-wire and an extra set of pedals (so you can have two people pedalling without the annoyance of normal tandem bikes having to pedal at the same rate), and a more powerful motor (only 250W is legal in France, where this was designed, whereas 500W is legal here in Canada)
Judging from this video, you could probably fit 4 or 5 in a standard car parking space. Obviously takes more room than a bike, but tbh I see these more as a car-replacement vehicle than a bike-replacement vehicle. Plus, these would weigh so much less than cars that it would probably be waaaay more cost-effective to build vertical parking garages for these things (like the ones in the Netherlands for bikes) than for cars.