SteamOS in the end is a hedge. Steam as a client / platform will still continue to exist on Windows, Mac, & Linux. Even though SteamOS will have "apps" such as internet radio services, netflix, etc. it clearly is not meant to replace a generalized desktop computer. Really its meant to go in the livingroom on steam machines where you won't be calculating figures in excel anyway. Eventually I think Valve would like to see the desktop OS move to linux as well since they will make money with their distribution service there. But Windows and Mac support won't be going away anytime soon.