Until the last sixty years, literary permanence wasn't bestowed, it was earned by an author and a work still being read and admired after many years of being published.
In the Sixties and beyond, critics and scholars started labeling current books as great and part of the literary canon. Not surprisingly, the books declared great have mostly disappeared into obscurity and only those of us forced to read these "masterpieces" in graduate school still remember them.
One major criteria of a work lasting is that one generation passes the book to another. If the book continues to speak to that next generation, it will continue to survive.
If anything, books moving from print into the digital format will make it much easier to pass a story from generation to generation because it won't be out of print.
On a side note, I've collected a few review quotes which have proven to be really wrong. Here are a few:
"Sentimental rubbish... Show me one page that contains an idea.”-- Odessa Courier on Anna Karenina by Leo Tolstoy, 1877.
"Shakespeare's name, you may depend on it, stands absurdly too high and will go down.”-- Lord Byron, 1814.
"His fame is gone out like a candle in a snuff and his memory will always stink.” -- Wm. Winstanley on Milton, 1687.
"Monsieur Flaubert is not a writer.” -- La Figaro, 1857.
"This is a book of the season only.”-- NY Herald Tribune on The Great Gatsby by F. Scott Fitzgerald.
"We do not believe in the permanence of his reputation. Our children will wonder what their ancestors could have meant by putting Dickens at the head of the novelists of today."-- Saturday Review, 1858.
"Nothing odd will do long. Tristam Shandy did not last.” -- Samuel Johnson in 1776 on a novel that has never gone out of print.
"The only consolation which we have in reflecting upon it is that it will never be generally read.” --J. Lorimer reviewing Wuthering Heights by Emily Bronte, 1847.