And what about altcoins that issue an unlimited number of coins at a fixed annual inflation rate? If we price them as you describe, their value is infinite. Th

And what about altcoins that issue an unlimited number of coins at a fixed annual inflation rate? If we price them as you describe, their value is infinite. The correct strategy is somewhere in the middle. Shares with pre-programmed future distribution (as happens in traditional mining-based coins) should contribute less to the calculated market cap as they recede further into the future, using some discount function that produces a finite, reasonable present value for coins with unlimited exponential growth of the coin supply. For coins with a central authority issuing distribution, the function has to be weighted by the credibility of the authority's plans. If some coin authors convince you that some portion of their coin will never enter circulation (e.g., if they publicly destroy them by sending to a vanity address so improbable that they could not possibly have a corresponding private key), you should drop those coins from your calculation of the cap entirely. If they merely promise to only release the coins slowly over many years, as with Ripple, your estimate of the market cap varies substantially based on how much you trust Ripple.