This works as an ending even of many don't like it. It's even darker if there's no following series.

Bakker could have killed the main cast. That way the themes would have been clear: they lost, everything was for nothing, Kellhus for all his cleverness was tricked...

This however is even darker. The No-God was summoned and the heroes survive. What follows is not an impossible win like in the last apocalypse, but a slow end. Those who died early where the lucky ones. Many wars follow, many heroes arise. Akkamian kills many Sranc and unites the nations under Esmenet. She is a fearless leader who fights tooth and nail for humanity. All the nations get together, even the Schilvendi tribes and non-men. The good in the hearts of men is revealed in the darkest moment...and all of this, doesn't matter. After all the countless heroes and surprising victories one thing remains unchanged : The Heron spear is lost. The No-God walks the earth. The gods can't perceive it... humanity dies a slow death...the end

This story is not worth telling because the end of it is inevitable . I can't think of another series where a lack of a followup makes the story even more fucked up. Really can't imagine how Bakker came up with all of this...damn