Frankly, I am bummed by this news.
I read the books, but seeing how it was a decade+ ago since I last went through some of them, most of it is a blur and I can forgive some of the changes in favor of smoother storytelling.
While the show brought familiarity back, and season 1 was painfully bad in almost all ways, from adapting/changing characters to lore. The show was leaps better in S2 and with S3 each episode felt very cinematic and now told a more cohesive story.
So, even though it was adapted, I was looking out for each new episode and had high spirits for a good S4.
Alas, if it is not picked up by any other studio, the "unfilmable book series" will remain that way, no one will burn their hands on it again. So, those cheering its demise, take that in consideration.
In closing, Prime definitely did not do it full justice at the starting line and it was expensive to catch up to that fact ...
But the show was treated and produced better than Rings of Power, which does get another stay and money pumped into it, a choice I rather saw turned around.