I think you are dismissing die-hards and fanatics in that equation.
There are still people that play Quake III and pay for servers even though the game is 16 years old. There is still a select few that still play.
I know bad example, except for those of us in the 30's age group.
Anyways my point is that there will always be a demand and use for bitcoin. If not by mainstream then at least by niche users and diehards. There are some people that wouldn't be able to resist buying 100,000 BTC for $10.00.

A zero price could only be achieved by a major flaw in the protocol that either revealed private keys, or allowed people to generate 'counterfeit' bitcoins.