The most accurate answer is that nobody knows. Over the years, various scientists have raised theoretical objections to time travel, but none have held up. Right now, there are scientists who believe time travel is possible, and even technologically feasible. Others believe it is not possible. In truth, at the moment it is just a matter of opinion.
Nobody is good at predicting the future.
On the contrary, writers and futurists alike are invariably awful. They miss the tone of the times, or the feel of the social structure. Kahn's book, written in the 1960s, Toward the Year 2000, was remarkable for predicting everything from the rise of the Japanese economy to the rise of the fitness craze to the vogue for spirituality. A remarkable piece of work. We are on the cusp of the millennium, and predictions about the future are at a fever pitch.