Our open source expert foresees the future of Linux: By 2012 the OS will have matured into three basic usage models. Web-based apps rule, virtualization is a breeze, and command-line hacking for basic system configuration is a thing of the past.
No discussion of Linux hardware would be complete without some discussion of hardware compatibility. Obviously there's going to be increased attention towards open-source device drivers for existing hardware, but another trend is the growth of hardware with open accessibility and standards. If any major hardware maker doesn't have Linux drivers for their product by 2012, either as a first-party product or as a community effort, they can expect to be singled out for it almost immediately.
Asus's "netbook" Eee PC and similar machines are just the first of what promises to be a healthy platform for Linux.
What'll you be running on Linux in four years? Chances are you'll be running a lot of what you have now, just with a new revision to the left of the decimal point. OpenOffice will be either in or fast approaching its fourth revision, with features like interoperability with Microsoft VBA macros, a native 64-bit edition and quite possibly an entirely new interface that isn't hidebound by the program's legacy requirements.
Another important thing to expect is the use of the browser as an application deployment framework, or at least attempts at same. This is already happening to a great extent on multiple platforms -- e.g., Gmail instead of Outlook or even Thunderbird -- but projects like Google Gears are aimed at making the desktop, the browser and the network work in both connected and disconnected ways.
As of this writing, a 1-terabyte consumer-grade drive has hit the market for about $175. In four years, a terabyte will easily be half that much, and a home media server with an array a few terabytes in size wouldn't be out of the question. One possible way to organize all of that space is through Sun's recently open-sourced ZFS file system, which allows easy growth and management of file systems.
Right now, however, the licensing for ZFS only allows it to be used in Linux's user space -- not an impossibility, but perhaps over the next few years Sun can allow ZFS to be relicensed in a more GNU-friendly fashion to allow it as a kernel add-on. (It's also possible to run ZFS in an OpenSolaris implementation such as Nexenta, along with all your other favorite Linux-y apps.)