How can you get hard evidence today for something that may happen in 25 years, considering the rate of change ? And I don't agree that it's pure speculation -

How can you get hard evidence today for something that may happen in 25 years, considering the rate of change ? And I don't agree that it's pure speculation - we do see how many jobs(in full or in part) could be, and may be on their way to being automated. On the other hand, we rarely hear reasonable speculations on what would be the jobs that would replace them. Considering the creativity of the human mind (and of various authors), and our love for speculation, that's somewhat worrying.