Would you say this a fair way to calculate the future value of the different cryptocurrencies...
Take Siacoin for example - essentially they are offering secure cloud storage. If you look at the value of a similar existing company offering this service, such as drop box, they have a market value circa $10B. One could then assume, if Siacoin take a similar market share in the future they will be worth a similar value.
I appreciate this is simplistic however trying to value the future potential without throwing stupid numbers at the valuations.