All we need is (1) to work with at any given time and it does not have to be a single chosen "ONE", like bitcoin.
It can be almost any of them that are built to last.
So, if the value is not in the bitcoin itself, then it has no specific value other tha nit's primary purpose for which it's most useful. the ones I just outlined.
Thought?
I agree with the first point, and that's why people are prepared to pay more for Bitcoin than say, the equivalent share of Feathercoin.
But I wouldn't go so far as saying its "fair price" is $0... it's like saying "hey, an online payment gateway only has any value if tonnes of places accept it... and that's why the value of paypal is $0"
On another note, say something with genuine improvements on Bitcoin come along, like Peercoin or Zerocoin, the improvements are not going to be so dramatic that every vendor in the world switches at once.
So if in some distant future when some new cryptocurrency comes out that solves some huge problem that cannot be solved with Bitcoin, the price of Bitcoin will still not suddenly drop to zero; people will take their time switching, because all the benefits of Bitcoin will still exist, and it will still be the most widely used.