Author: Jerry Pournelle
Heinlein never had a best-seller. Even, I think, with Stranger in a Strange Land, I don't think it was actually on the New York Times best seller list.
Somebody's always getting me to come lecture to their writing class, and I don't talk about writing at all, I talk about the business of making a living at this racket.
We do a hard fantasy as well as hard science fiction, and I think I probably single-handedly recreated military science fiction. It was dead before I started working in it.
You no longer have much in the way of knowing what to do in a big, epic novel about the future, because nobody knows what the hell is going to happen.
So, I guess the answer to your question is very few people can bring off a novel of the future because it's just so damn hard to make it look like the future.