1. Most of the digital currencies are deflationary. - their supply will end over time.
2. The value of a crypto-currency is not only in its market cap but lies also in its technology and use.
3. Not all currencies will survive - these networks depend on adoption to survive. But we are heading towards a multi currency future.

I'm not sure if this clears up anything.I've been into this only for a year now. I feel the word Token is more accurate than using the word currency. :)