As John Scalzi said, I kicked a small genre hornet's nest yesterday with my comments about the fossilization of science fiction and fantasy literature. The comment which seemed to resonate the most is that young people are not finding their way to SF/F through the genre's classic authors like Asimov, Clarke, Heinlein and Tolkien.
Among the people responding to and generally supporting this view are Adam-Troy Castro and Scalzi, who added that "The surprise to me is not that today’s kids have their own set of favorite authors, in genre and out of it; the surprise to me is honestly that anyone else is surprised by this."
Because of this attention I want to expand on my comments about these classic authors. Asimov, Clarke and Heinlein — the Big 3 as they're called — were my introduction to science fiction, while Tolkien didn't introduce me to fantasy but was a close runner-up. But I first read these authors decades ago as a child. I also found their works in my grandfather's Golden Age SF collection at a time and place when finding any genre literature was difficult (at least in the rural area I grew up in).
I love Asimov, Clarke, Heinlein and Tolkien but expecting their works to resonate with new readers is ridiculous. With luck new readers will come to love SF/F through new authors and then discover these classic authors. But don't be shocked if that doesn't happen.
In addition, new readers may be exposed to the genre through adaptations of these authors' works. My kids, for example, love the film versions of Tolkien's novels. But they have not enjoyed the written versions of his stories, even though they generally love fantasy literature.
A few years ago I was on a SF/F panel about bringing new readers into the genre. I mentioned that SF needed more gateway novels, at which point the other author on the panel snorted and said we don't need new gateway novels ... the Heinlein juveniles are still perfect.
That is the type of attitude which people should fear because it will kill our genre. But new readers not discovering SF/F through the classic authors you grew up on — that's nothing to worry about.