If one counts Android as “Linux”, then it’s probably fair to say that nowadays most people already use “Linux” on the client side (the server side has been prominently GNU/Linux for a very long time) and if one counts Chrome OS as GNU/Linux (technically it is), then it seems reasonable to expect 10% market share by year’s end or some time next year

Source: LXer – On the Client Side, Linux Has Become Market Majority