Concluding a trilogy can’t be easy. A long train of character arcs, plot twists, themes, motifs, and denouements must be accounted for. That is unless you are Douglas Adams, and can surmount this challenge by entirely ignoring it with a barrage of random, winning silliness.
Not every reader can be bought off by cosmic gags or pratfalls without some closure as to what it all means. But take your pleasures in life where you can. You don’t have to love Life, The Universe And Everything to appreciate it for what it is rather than what it isn’t.
One thing it certainly isn’t is the end of the trilogy, third book or not.