The Lord of the Rings achieved popular acclaim long before Peter Jackson even conceived of filming the work. LOTR appeals to mass readers, not only to niche genre aficionados. Its presence is felt worldwide, even beyond the pages of fiction, influencing the development of everything from video games to political sloganeering. The books continue to be printed, new editions appearing all the time.
Will any other work of fantasy fiction ever manage anything near such universal crossover appeal? Does it matter? I suppose not. My appreciation of something is not dependent upon its popularity. Still, the question occurred to me.