MNblockhead
A Title Much Cooler Than Anything on the Old Site
The initial game where this rules engine came into being is Dragon Age (the TTRPG adaptation of the CRPG).
Much later the IP specific details were stripped out and a generic Fantasy AGE product was published.
However, with the exception of M&M, and Freeport, Green Ronin is notorious for abandoning properties as soon as the easy initial sales are done.
(It doesn't take a genius to explain why you haven't heard of AGE before - there's simply no support. Of course the engine languishes in obscurity!)
I would hope that that the popularity of the books and TV series would make an exception for the Expanse. On the other hand, its strengths are its weaknesses. The Expanse is a science-based scifi setting where both the protagonists and antagonists are almost elusively human. It is not a kitchen sink Fantasy in Space setting like Star Wars, Star Trek, Doctor Who, or Starfinder. But the lack of diversity in settings, species, class options, etc. could lead folks to tire of it quickly. This is an argument for publishing well-written adventures to support it. Give some more options, perhaps create an "expanded universe" setting for the RPG.
On the other hand, even if I only run a mini-campaign or the occasional one shot, it is still a good investment for me. It provides a very different setting supported by a set of easy to learn mechanics that are well suited for the setting.
Even if I only get 16-32 hours of enjoyment out of it (reading the materials and running a couple games), it still ranks low in per-hour entertainment costs.