First of all I am migrating my systems to Ubuntu Linux, I am eating the dog food I am talking about. I've used Linux off and on since 1995, and Linux has been out since 1991 when Linus Torvalds first released it to the public. I just converted my Acer Laptop from Windows 7 Home Premium to Ubuntu Linux 12.10 AMD 64 bit version. My PC, a custom built ATX system will dual-boot Windows 7 and Ubuntu just in case I need Windows for some application but I am not going to Windows 8.
I am learning the built in C/C++ compiler GCC for Linux using NANO for the command line, and GEdit for the GUI GNOME editor. They both highlight my code and show me the structure. No more Visual Studio, as I switch to Mono.
Apple claims there are and estimated 66 million Macintosh users, 27 million of them running Mac OS X 10.7 Lion. According to the Linux Counter there are an estimated 63 million Linux users in the world. According to Netcraft over 200 million Web Servers run Linux with Apache, and Microsoft Windows Server with IIS only runs 97 million web servers. Windows 8 sales are slow, reaching 4 million users so far, which is slower than the rate of Windows Vista or Windows ME when they came out.
What is the deal with Windows 8? Microsoft changed the way that the GUI worked removing the start menu and adding a start screen which they got sued over the name Metro, called it Windows 8 GUI, and now call it the Modern GUI. With the Windows 8 Surface Tablets Microsoft wants to take a bite out of Apple, and the cheaper Windows RT tablet based on ARM instead of Intel processors won't even run Legacy Windows apps, but it is a twin for Windows 8 that has people confused. The Microsoft Surface is to the Apple iPad, what the Microsoft Zune was to the Apple iPod. The Windows 8/RT Surface Tablet is the New Coke of Microsoft Windows, and people are asking for the Classic Windows GUI back already.
Yes corporations are finding problems with users learning the new Windows 8 Modern GUI, it has a high learning curve and in many ways it is confusing. Rolling out a Windows 8 upgrade has many hidden costs, training costs are through the roof and converting custom applications to the Modern GUI is time consuming and very costly as well. The Modern GUI is really designed for touch screens and mice and trackballs and trackpads don't work with it too well. So to be upgraded to Windows 8, the corporate PC has to have the monitor upgraded to a touchscreen for best results as well.
From the corporate rumblings they are giving Microsoft 1 to 2 years before they consider a migration to Linux and free and open source alternatives to Microsoft software and products. Linux can have any GUI you want, just install a new GUI and then choose it when you log on. There is Unity with Canonical's Ubuntu or you could replace it with GNOME or KDE. If you want a more Classical Windows look try MATE, if you want a Mac OS X look and feel with a dock try Cario Dock, you can use more GUI enhancers and even custom skins to make Linux look like whatever you want it to look like.
Need to run legacy Windows apps? Consider QEMU for running and old version of Windows in a virtual machine. Another free virtual machine is Sun/Oracle's VirtualBox. Of course VMWARE has Linux client and servers as well.WINEHQ is an environment to convert Windows libraries and API calls to Linux, it is not an emulator but attempts to run Windows code on Linux. WINE is not 100% Windows compatible but can run a lot of the older software under certain conditions.
Why Linux over Windows? It has better security than Windows will ever hope of having. Linux has a lower overhead than Windows and it runs faster. The Linux kernel can load modules in and out of memory as needed to save memory and CPU cycles for modules not accessed frequently automatically while Windows loads a ton bloat of services, memory resident programs, toolbar apps, updaters and has such poor management that it can cause system crashes and blue screens of death.
Why Linux over Mac OS X? Well in order to run Mac OS X you need an Apple branded computer, a Macintosh, and those are always expensive. You can run Mac OS X on Non-Apple branded computers, PC Hardware as a Hackintosh, but you are breaking the terms with Apple and the software laws which is risky. Linux is free to download and install and use, and like Mac OS X it too is based on Unix standards. Linux will run on almost any PC as long as it has driver support for all of the hardware, which happens to be more driver support than Mac OS X itself and also more driver support than Windows 8 or Windows 7. In fact your old PC computers can be given new life by installing Linux on them. Recently Linux dropped Intel 386 support, but it still supports Intel 486 and up PC computer processors and AMD chips and has been ported to many different processor types as well. You still need a Mac to write iOS apps for the App Store and you need XCode to submit apps to Apple's app store along with a $100 fee for a developer's license. Linux is not that picky.
Android phones and tablets are based on Linux technology and Linux mobile devices have been out since before Apple got into mobile devices as PDAs, cell phones, tablets, and other embedded devices. A lot of the patents, copyrights, trademarks, and IP that many companies claim to hold where developed by the Linux open source community first and dating back as far as 1991 with the original Linux, that was designed to be portable to different platforms. Linux pre-dates Mac OS X, Windows 95, the 32 bit OS/2 2.0, and many others.
I don't see a "mass exodus" to Linux any time in the future, but I do see home and corporate users migrating to Linux because they are tired of Microsoft's tricks and failures, and don't wish to pay Apple's high prices, and look for something more reliable and lower costing for them.
By all means a majority of the market develops software for Windows, and after that develops it for Mac OS X, but ignoring Linux at this time and phase would be foolish. You have to consider it at least a third system to consider using and developing on.