Gaiman's work is complex, drawing on many cultures and religions. However, this part of it is strongly influenced by Norse mythology.
The farm is the site of the World Tree (Yggdrasil in Norse mythology). The three women who hang Shadow from the tree are the Norns. The Norns represent the past, the present, and the future and are said to shape human destiny. Shadow himself is the child of Odin, who hung himself for "9 days and 9 nights" from Yggdrasil in sacrifice to himself and achieved wisdom thereby.
When Shadow first arrives at the farm (chapter 14 in my edition), the farm is run-down, but the Norns are strongly present - tying him up and hanging him from the tree. Laura visits him in Ch 15-17 and receives a drink of water from the well on the farm (Urd's Well, Urd is one of the Norns), and this extends her revenant state, however this indicates that the Norns are still there. When Mr Town visits later in the same chapter, the farm house is abandoned and decaying, but he sees a vision of the Norns out of the corner of his eye, showing his fate:
He carried the ladder back to the farmhouse. From the corner of his eye he thought he saw something move, and he looked in through the window, into the dark room filled with broken furniture, with the plaster peeling from the walls, and for a moment, in a half-dream he imagined that he saw three women sitting in the dark parlor.
One of them was knitting One of them was looking directly at him. One appeared to be asleep. The woman who was staring at him began to smile, a huge smile that seemed to split her face lengthwise, a smile that crossed from ear to ear. Then she raised a finger and touched it to her neck, and ran it gently from one side of her neck to the other.
By the time Horus and Easter come to cut Shadow down, the farm is completely abandoned.
This shows the Norns abandoning the tree of life, and is perhaps symbolic of the abandonment of the world to modern thinking and gods. Fate left to chance perhaps.