It is 100% what will happen in the future for tons of reasons. It makes more sense as people download things to have access to them at a later time. The cloud is the cloud, independent of physical devices which do get lost and will not always continue to work. + Cloud storage has become a commodity.
Why isn't cloud download as default already happening? Sure, not everyone buys enough cloud space to have downloads be to the cloud by default, but it should probably already be an option in browsers/devices since lots of people do. Why isn't it?