There will be competitors.
The hyperinflationary ones won't last.
The winning p2p cryptocurrency might not be Bitcoin, but the concept of a p2p cryptocurrency offers new features that are in high demand with a lot of people in the world, so it's more than just a fun new toy that will lose its appeal after the hype is over.
Why are you so absolutist about Bitcoin's future? Complete failure <=> Huge success is a false dichotomy.
There is no reason that Bitcoin can't remain sustainable as a secondary currency such as the CHF or silver, or even as a niche product.
One of the closest things to Bitcoin prior to its arrival was Liberty Reserve.
According to Google Trends, Bitcoin has already overtaken Liberty Reserve in popularity.
http://www.google.ch/trends?q=bitcoin%2C+%22liberty+reserve%22Liberty Reserve has been a successful niche product for several years now. Why can't Bitcoin?