Windows will never be threatened by Linux. First of all I use Linux, Windows and Mac OS X in an Enterprise environment. The biggest reason why Linux will never over take Windows is cost.
Before you pull out you pitch forks fan boy me to death you might want to listen to someone that has daily real world experience with all the OS’s.
Yes Linux/Android is free of Licensing cost, free to download and free to use, but not free to make work or harden or maintain. You have to pay Devs and coders (They are not cheap) to build the Linux system for your use. Harden it, update it, and maintain it. Android does not work out of the box and has to be specifically compiled to work with whatever hardware or platform you want to use. This again cost tons of money to test and maintain.
Windows, yes you have to pay licensing fees to use, but guess what. It can be install on anything and it works (Per say the third party drivers don’t have issues)
We IT Exec’s use Linux on servers because once we spend the extra money on making it work. It will work till the end of time 24/7, but it was by no means free. Unfortunately now with Virtualization and Windows server platform actually becoming more attractive in performance, security and most of all deployment and maintenance cost, Linux is starting to lose ground in the one area it held the most, in Enterprise again due to COST operation and maintenance.
As far as desktop and workstations, you are absolutely retarded as an IT Administrator or Director to use Linux as a desktop OS and just thinking about maintaining Linux desktops makes me twitch. Active Directory and Group Policy trump anything Linux has out there for controlling stupid users by a land slide and not even going to Open Director of Mac OSX.
So all you Linux/Android fan boys, this is not a hate on Linux but a reality check. Using it on your personal computer that you personally maintain does not translate to the real world use of the system as a daily driver for the world. There are countless reasons why Linux will never be the main OS in the world and the big one is it does not cater to the lowest common denominator. (The 80% of idiots in the world that can’t even use Windows let alone an OS that takes more than average intelligence to operate)
So when you rant Linux to save the world is great in all but it will never rival Windows and Android is nowhere close to a desktop OS.