As the sustainability of genre fiction is a topic of perpetual discussion, it seems there is nothing new under the sun. In April 1954, a spirited exchange in print occurred between John Wyndham Parkes Lucas Beynon Harris (aka John Wyndham, author of Day of the Triffids, 1951) and Morna Doris Brown (aka E. X. Ferrars [US] and Elizabeth Ferrars [UK], Detection Club member and a founder of the British Crime Writers Assn).
Wyndham theorized that a shift in New York publishing to science fiction was because "there has been too much murder going on for too long." He stated, "The number of people who are bored with routine detective stories has been increasing. . . . The present outbreak of rockets may be seen as the assault weapons softening up the detectives" (1–2). He dubbed some fictional detectives "long-toothed bores." However, he does not reserve his criticism to mysteries, addressing weaknesses in his own genre ("Wells's conceptions degenerated into a kind of super-gadgetry"). He also cited his choices for exemplary works (Vonnegut's Player Piano, Orwell's 1984, Lewis's cautionary It Can't Happen Here)—perhaps implying that mystery fiction could not propose their equals.
Ferrars, in her reply, pointed out that The Brothers Karamazov is a detective story and that both Shakespeare and Sophocles were concerned with murder. She also listed the strengths of the genre: "The detective story must deal with human emotions, with violence, fear, guilt, suspicion, courage, intelligence, and moral values . . . suspense must be created, curiosity stimulated” (2). Science fiction, she asserted, "cannot be redeemed by answering that fascinating question, whodunit? or give the reader the satisfaction of winning or losing in a game of wits with the writer."
Thankfully, Wyndham's prognostications have not come to pass. Indeed, it's hard to imagine one genre's fans doing a whole-scale jump to another, especially if they enjoy reading across genres.