Here's the list you all generated in class the other day about books that are popular now that may or may not become classic in the future. Please feel free to add others in the comments.
Popular now, classic in the future
Stephen King (It, King as best of genre)
Game of Thrones
The Book Thief
Cyanide and Happiness (web comic)
A Child Called It (pain memoir/abuse memoir)
In the middle (might be classic in the future but maybe not)
Popular now, NOT classic in the future
Da Vinci Code
Nicholas Sparks (any novel)
The Girl with the Dragon Tattoo
Note: I've added an option that addresses this to the Paper 4 assignment: "In keeping with our "popular then/classic now" theme for the course, choose a current book that you think may become a classic in the future and write a serious, extended analysis of it explaining its literary qualities. You might want to choose to compare it with a book that we've read or discuss it as an example of a genre that we've discussed."