It's probably also worth noting that widely-known and accepted prediction will, in turn, have an influence on what they predict. When a physicist has an idea for a very expensive experiment that may lead to nuclear fusion and has to get funding, he's more likely to get funding from an agency that feels that nuclear fusion is 'just around the corner' than from one that feels that nuclear fusion is 'impossible within the next fifty years'.

And before that, of course, the physicist himself has to decide in which direction he will take his research. The R&D departments of commercial enterprises will usually want to direct their research towards outcomes that are likely to result in something that can be solved, and therefore sold, reasonably soon. Therefore, most commercial enterprises are unlikely to run across any unexpected insights.