PS - I didn't know a lot of the terms you used, but the Finite State Entropy (FSE) link you provided does a good job intro'ing some of them, and the linked paper Asymmetric numeral systems: entropy coding combining speed of Huffman coding with compression rate of arithmetic coding [4] (ANS) seems interesting.
[1] https://github.com/Cyan4973/xxHash
[2] https://github.com/rurban/smhasher
There is a lot of other gem in his blog. He points to resources and other people he have worked with making it much easier to get a bigger picture on the related items.
I don't think he is the first; although RAD game tools has been cagey about the details, many strongly suspect their recently announced Kraken, etc. use ANS in some form and some of their previous products; see the discussion here:
https://news.ycombinator.com/item?id=11583898
...and here:
But even with that Yann might be the first. Yan's work on FSE is old [0] and if I'm reading this correctly his work on FSE is a mix of his own work and Jarek Duda. But it seems one of his failed attempt challenged Jarek to invent another version of ANS called rANS [1] and as you can see in the encode.ru comments from the RAD game tools that they seem to be using rANS at least for Kraken. Regardless these are impressive works and these people are bouncing ideas of each others, being challenged and inspired which is a very good thing for the rest of us :).
[0] https://fastcompression.blogspot.com/2013/12/finite-state-en... [1] http://encode.ru/threads/1821-Asymetric-Numeral-System?p=360... [2] https://github.com/rygorous/ryg_rans
[0] http://cbloomrants.blogspot.ca/2016/07/introducing-oodle-mer...
[0] https://fgiesen.wordpress.com/2015/12/21/rans-in-practice/
[0] http://encode.ru/threads/2577-Open-source-Kraken-Mermaid-Sel...
[1] https://github.com/github/dmca/blob/master/2016/2016-08-30-O...
i.e. download speed is up to 20% faster with Zstd as compression algo for backing store compared to Deflate. Assuming bandwidth is available ;)