A friend said to me: “Writers who don't adapt to the changing environment won't survive as professional writers. If the bookshops go, the publishing houses may go. No more advances or royalty cheques, however small.”
When you indie publish, you don’t get an advance on your work. You pay up front, either the capital costs of producing print copies of your work (not insubstantial) or the smaller costs of publishing directly to a digital format.
What if there were no more hard copies? What if tree books became obsolete? I don’t see this happening in the near future, though who knows where and how we will be in fifty or a hundred years’ time.