First, I think we should wait a while and see if she is really dead.
Whether Anne Rice's books will be remembered as much as Tolstoy, depends upon the academic world. There is world of people who gave up on selling their own work and now make a living by writing about other people who write for a living.
One of them will write a paper, which is weird because most of us write on paper, and expose some arcane structure in Rice's prose, which proves Anne Rice was really Jim Morrison. Other academics will argue about it and then it will all become required reading, which means more papers are written, and eventually Rice will be the equal of Tolstoy.