Chances are, when people look back, although they will always credit Feynman for setting things off and K. Eric Drexler for extending and pursuing the vision, they will probably look at the 1990s and early 2000s, not the 1960s, as the time when small began to be a reality. Feynman foresaw many of the problems troubling today's researchers. Even so, he believed in 1959 that it would only be ten years or so before the entire Caltech library would fit on a single library card. That's still a long way away, even though at least some MEMS research focuses on high-density computer storage. And we're even further from his wilder imaginings, such as the notion that you could swallow a mechanical surgeon that would look around and repair organs.
More recent estimates center on the middle of the next century.
Feynman, however, had no doubt that it would all happen.