From my understanding, any comparisons to FIAT, instead of the current bellweather cryptocurrency, are irrelevant. I am curious if the comparison will change with BTC's continued relative decline in market percentage? Could be Ripple or Ethereum with the red arrow in the future? Of course, market capitalization dominance may not directly translate to higher performance in all cases. Curious if efforts will be made to group Cryptocurrencies into Large, Mid and Small cap markets? Could help to illustrate potential investment risks, relative to a currencies market share with like sized peers, and the market as a whole?
It's not so much a comparison to FIAT or to BTC. It's more like a recognition of the fact that most cryptos are denominated in BTC, like e.g. the US stock market is denominated in USD, and e.g. Japan's stock market - I'm taking a wild guess here - probably isn't denominated in USD.
Now within that - of course, there are comparisons by large/mid/small cap, industries, etc... Top 10 coins by market cap (excluding the ones with asterisks) can be a better gauge of where the market is going than BTC or ETH alone.