Everyone's got their own closed ecosystem and it's incredibly annoying, so this would be a breath of fresh air. And, yep, we're all inching closer towards this becoming a reality:
For a vast majority of people, a cell phone bought in 2014 is going to be enough for essentially everything they use a PC for. Desktops will still exist for some folks, but it's far more convenient to carry around a single device that can store everything you've got (cloud or local) and be all things to (nearly) all people. It's like Batman's utility belt except with pornography.
Celio had the Redfly device for this Windows Mobile a few years ago - had one, worked great - they promised a way to use it with Android, but it never came out