Personally, I see no reason to dismiss the concept. Fabrication technologies advance at different rates, and it's certainly possible for plastic to catch up with metal or carbon fiber for bike production. But those technologies keep improving too.

Another thing to consider is that the cost picture for fabrication depends on where you're located. In my own work, I've made assumptions about what technology is the most cost-effective based on my familiarity with industry in the US, only to have those ideas turned upside down when production is taken to China.

At the same time, a new "bike of the future" concept is introduced by a design student or studio, roughly every 15 minutes.