Assuming Apple isn't ready to walk away from whatever revenue still comes in from downloads, it is probably a matter of time before it happens. But at this point, there is still a perceived value in owning music.
The future of music is streaming, not downloads. But that doesn't mean Apple, the company that essentially invented the market for music download sales, is going to stop selling downloads anytime soon. That's contrary to a report that said Apple planned to stop selling downloads in two years — or, alternately, "the next 3-4 years."