Roaming profiles exist longer than today. I read a lot of articles about home servers over the period of a year. Why not leave the maintenance up to the people that have years of experience. I think the only thing that is stopping this is the perception your internet connection can break but i think that could be solved by joined provider accounts to create parallel connections.
Content providers will need to have regional servers to provide the fastest connection to your files. But think of a code provider that offers a development environment you need by clicking a few checkboxes. A lot of projects already have subversion servers so their source code is online already.
What makes my live easy are the applications i run not the OS, most functionalities of the OS’s are interchangeable. As a webdeveloper i rather learn about maintaining a server than keeping my OS running.
For entertainment i would love to connect to my files on every computer, cellphone, tv, stereo-installation, ... . I just saw this weekend a video where a quake game was played on an iphone by moving the device and tapping the screen.