Putting a correct economic value on any item is not a straightforward task. There are different methods, different purposes, different uses.

I agree that the current default market cap metric that is often used is flawed and the introduction of another metric to give an insight into the coins future is welcome but whatever metric is introduced will be subjective to say the least and probably not comparable across coins. What value would you use for USDT for example? Future Coin supply would be a subjective assessment of future investments in the coin.