New operating systems get everyone's customers to buy new things to make the new operating system more comfortable in its shabby, legacy-tastic new environment; all the new stuff makes the paint look dingy and the rug look dirty so pretty soon those have to go and in come more companies to replace paint with Paint! And clean the carpet by converting it to FLOoR and to make the rest of the company's employees jealous of the ones running a new OS with cool new hardware and excellent new Pant! And FLOoR, so the company buys more operating system.
When Windows 95 came out I combed my hair and picked all the spinach out of my teeth and drove to a studio to be interviewed remotely on CNN about Windows95, that was coming out that day.
Making a choice without guidance from a monopoly
"So what do you think?" the anchor asked after she took the feedback from a pre-taped story about how much better Win95 was than Windows 3.5 (so was cuneiform).
"Should we all rush out to buy Windows 95?"
I took her at her literal word instead of the implied one, and explained in what circumstances and for whom Win95 would be a better option than Windows 3.5.
The truth was it didn't matter whether Win95 was better or worse than 3.5; people were going to buy it anyway, or get it when they got their next computer because they didn't have a choice.
Microsoft owned the OS market except for a few arty types running Macintoshes and a few ultra geeks running Unix on their desktops and some luddites sticking with DOS.
That's still true, mostly. You have to go out of your way to avoid Windows on a new PC. Even if you buy PCs by the skid-load and get to specify component that goes into them, you still have to write into the contract that you don't want Windows and that you'll be responsible for the licenses of whatever OS you end up loading because PCs are no good without operating systems.
If Windows is a choice, remember there's more than one answer
Microsoft is nervous because you're more likely to buy a Mac than you have been in decades, more likely to buy a phone or tablet than a laptop than you have ever been, and more likely to put something other than the latest version of Windows on any kind of PC – whether that means Linux or XP or exist licenses for Windows 7 or Android or iOS or even WebOS.
Because Windows is no longer the only game in town. OS X Android and iOS and VMware and Citrix haven't run it out of town on a rail, but the next campaign for mayor isn't going to be a cakewalk, either.