I think what we are bound to see in the coming years isn't the death of one or the other, but an inclusion of a unified operating system that ties everything together seamlessly. Computers with multiple desktops, that have CPU's and GPU's powerful enough to stream those desktops to your tablets so you can work on the go around the house, or access your movies from anywhere there is a solid internet connection.
The SteamOS is brilliant.. but it's very limited because of the operating system's limited support for hardware drivers and video streaming (a quick OS transition feature would be nice as well.. like a "boot to windows" button).. the only thing microsoft can do to combat this is to have their software engineers design a "game mode", so to speak, of windows that basically puts it into a "light windows" mode in which games can draw even more power from the system.
The biggest difference between PC's and Consoles.. and the primary reason why mobile gaming is gaining such enormous ground against consoles.. is that PC's are not "family" or "social" gaming machines.. they are for one person to sit down and play a game, and yes I understand that playing online can be considered social, however in this context I am talking about real social contact not online.. and consoles, while they deliver the social and family gaming, cost hundreds if not over a thousand dollars to get started.. Valve has the right idea bringing PC's into the living room and that is the direction home computers should be headed anyway.. keep it in the living room and use a small cheap $50 device to stream the computer's desktop over wifi or something (and add some USB ports) to a monitor for work use since you won't need the full capabilities.
My entire point in this is what I said at the top.. in order to evolve.. someone, or Microsoft, needs to create an operating system from the ground up, that is built around the new technology we have today.. not a rehash of the old crap. It needs to work synonymous with tablets, it needs to be best friends with your phone and it needs to be able to utilize the best features that are available today such as streaming videos, games or otherwise to all the devices that most families that own a computer already have. This is the technology revolution and the foundation needs an overhaul or its going to crack, crumble and collapse.
Just my opinions.