It's entirely based on the generation reading it. For example, reading the Time Machine today, we might think it's an eloquently written classic. Reading it at the time it was written, many people probably saw it as trash. A great deal of the early genre fiction writers were not taken seriously, their stories being published in the equivalent of a sleazy magazine or comic book. Only with age have they developed a following and become regarded as classics. So, we can't really judge today's literature by the same scale. Only time will tell which ones will survive to become classics.