No. Even if we assume a magical device that stores nothing, cloud storage is still backed by guess what? hard disks. And this time, heavily redundant to ensure low latency and high availability.
So no, moving everything to the cloud, tomorrow, would vastly increase hard drive sales permanently. Oompff! http://allthingsd.com/20111005/it%E2%80%99s-all-about-conten...
Here's an example. I upload a video to youtube. youtube converts it into about 8 formats (depending on the initial quality; (mobile + flash 8/10 + html5 ogg/webm) * multiple resolutions), stores the original, generates dozens of multiple sized thumbnails for the seekbar, farms these out to multiple data centers, and then stores a bunch of metadata along with that (every like/dislike, comment, playlist, landing source, geoip of user). You are looking at something like 15 times more space needed for the cloud architecture.