In my mind, while it is applicable to English when taught in high school, 1984 is a book that is probably better suited for college students, as it can be a more difficult read and has themes that require a bit more thought than some other high school literature.
Of course, students would gain the most if the book was first taught in high school, and then later revisited in college. However, that would require coordination on behalf of both the college and the high school, and as such, isn't, in reality, a very practical concept.