Windows 8 irrelevant
W8 has no true bearing on the market, it is un unwanted system that is being installed by the few people that don't understand that "choice" is something they can have. W8 is a dead in the water.
What is far more important is the trend that will be created with Windows 10 ( W10 - ie : the North Kensington Edition - hint - look up London postal areas in order to understand ).
Windows 7 is rock solid and appears to be "relatively" secure. Hopefully W10 will provide the extra effort required to make it seriously secure.
The problem I see with W10 though is that it will become synonymous with Office 201x ( >= 2013) and the various Office Web editions which for the moment are unliked ( those interfaces make ones eyes scream). MS have to come back down to earth and fire the bloody interface designers that they have had of late.....
I really can't imagine where the Tablet market is going though as it does have an influence on the PC market.
[Relatively = in relation to previous MS efforts]