While I understand your reasoning behind seeing RVX as having much bigger market potential, I don't see the differences as being THAT significant....its not apples to apples, but I think calling it apples to cookies is a bit of an exageration....more like Apples to Tangerines.  

Relypsa got $1.5 billion for a drug that was FDA approved....208 isn't approved yet.  And doing some reading it seems that this Valtessa's sales have been pretty anemic...in 2016 it was just $13 million according to what I'm reading, however peak sales are seen as being around $700 million p/yr.

It seems that after Astra Zeneca's version of Valtessa failed to garner FDA approval they bought out another company, ZS Pharma, for $2.7 billion and now have Lokelma on the market to compete against Valtessa.

https://pharmaphorum.com/news/az-to-file-potential-blockbuster-potassium-drug-in-asia/

With our MC not even at $0.5 billion USD it gives us something of a benchmark....a fuzzy one in that these are now approved drugs, but a benchmark none the less.  

We've got a lot of ifs to overcome...."if" BETonMACE succeeds is the first and imo biggest hurdle.  After that comes CKD, Alzheimers and Fabry Disease.....and then any other trials that follow.