I recall him talking about how every school kid on Earth will eventually issue their own currency. I for one would not accept Tyronecoin if I was selling him some crack. I'd want something that the majority places a value on.
I think one way you could look at that is that the currency would correspond directly to the value of the person, or the value the person can provide.
I am actually interested in seeing an experiment based around this concept. I am confident, however, that all the value would gravitate to one person's currency, and all the other currencies would be small mediums of exchange for individual people.
That or an entrepreneur would aim to take the largest market share as quick as possible.
I do agree, however, that individual currencies will not be very valuable in the future, and will likely have no place in society.