There will be competitors.
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.
Not absolutist, just questioning.
I agree it could well have a niche that lasts for a long time. So not a "complete failure", as you put it.
But there just seem to be good reasons to believe it's unlikely to go mainstream, or be a "huge success".