So the interwebs suggests that Windows 9 will be released by 2015 and Windows 10 will be a pure cloud OS, aligning with Office 365, XBox Cloud thing and whatnot.
Could you imagine using a OS which is solely in the cloud (*)? With some countries still lacking behind in decent internet, I don't see it working. We probably talk 2016/7/8 here but still ... My area doesn't even have cable and our local ADSL provider suggests fibre by the end of 2015 at 10Mbits max.
(*) Talking as consumer and not business
My own knowledge base made public: http://open902.com