Technically, Microsoft pulled the plug on its free upgrade offer to Windows 10 a long time ago—in July 2016, a year after the OS was released to the general public. However, Microsoft still allowed customers who use assistive technologies to upgrade at no cost (opens in new tab). Barring another deadline extension, that offer is finally coming to end, with today being the last day to upgrade for free.
The offer was always intended (opens in new tab) for people with various disabilities who are unable to use their PC in a conventional manner. They may require a screen reader, eye tracking technology, or specialty accessibility hardware. Though Microsoft toyed with the idea of removing the upgrade tool and having customers call support to request an upgrade, it remained online, available to anyone and everyone through the honor system.
Whether Microsoft was more interested in bolstering its Windows 10 footprint regardless of how people got there or didn't want to open a can of worms by trying to determine what exactly constitutes having to use assistive technologies is irrelevant—the free upgrade offer disappears after today. Well, maybe.
Microsoft has extended the deadline in the past. Most recently, the free upgrade offer was supposed to end on December 31, 2017, but then Microsoft pushed the deadline back to January 16, 2018. It's still possible that it will get pushed back again, though this late in the game, it's best to assume today is the last day.
According to Statcounter, Windows 10 and Windows 7 are virtually tied in market share, each one accounting for just shy of 42 percent of all Windows PCs. Windows 8/8.1 stands at around 12 percent.
That isn't reflected on Steam, where the most recent hardware and software survey (December 2017) shows that around 70 percent of Steam gamers are running Windows 7, versus 25 percent running Windows 10.