Umm, The Sword of Shannara is explicitly set fifteen centuries after World War III, its sequel features a pilgrimage to the ruins of San Francisco, and Tolkien's trolls didn't wear radsuits. No judge or trial jury outside the British Commonwealth not otherwise in Tolkien's or his attorneys' idiomatic back pockets would give that lawsuit the time of day, not even his biggest American fans.
I'm not talking about the sequel. Elfstones is fine - the issue is Sword. Which has... Frodo, Sam, Gollum, Gandalf, and Tom Bombadil, among other things:
https://en.wikipedia.org/wiki/The_Sword_of_Shannara#Similarities_with_The_Lord_of_the_Rings