The issues I see with preventing bike theft include that its just so easy to take parts off of one, so even if you could prevent taking the whole bike some of the other parts have value too.

Only solutions I see are, having secure parking for bikes offered for pay, as benefit of employment, or venue provided. What makes a bike a pain to store besides length is the handle bars and foot pegs stick out. So design a handle bar with a pin so it can be rotated alone the bikes axis when parked and folding pedals. Then you can box store them narrowly akin to bus lockers.

Still the primary deterrent to theft is putting it where its at risk and if that means not taking it, well.