DN 3 D wasn't released in 1997. It was actually released in early 96.

Concerning Harry Potter: I seem to recall reading an interview with Rowling where she states most of the events of the books take place during the 1990s. This would make the epilogue of the final book actually the only scene taking place more or less during the time of publishing.

And it seems all of this is only because the author wants the story to become real life.