What's popular? Dickens wrote serials for magazines. Shakespeare wrote plays that appealed to all audiences. These were not considered 'great literary works' at the time, but lots of folk liked them.

Not necessariy all of an authors' work, either. Conan Doyle wrote a shedload of stuff, but is mostly remembered for Sherlock Holmes. Who now remembers the incredibly prolific Edgar Wallace? Will Ian Fleming be remembered for James Bond, or for Chitty Chitty Bang Bang?

My personal hope is that JRR Tolkien and Sir Terry Pratchett join the ranks of the immortals, but I have my doubts!