Science fiction and fantasy are now officially part of American literature. Houghton Mifflin Harcourt's famous "Best American" series, which features annual anthologies of the best fiction, essays, and more, is starting up a "Best American Science Fiction and Fantasy" series in 2015, presided over by award-winning editor John Joseph Adams. In 2015, his guest editor will be bestselling author Joe Hill.
I hate to sound like an angry old nerd but I don't feel like works of Sci-Fi and Fantasy should need validation by a large publisher to be considered literature. By their very nature they provoke thought in the reader even if they're not aiming for "literary merit".