Re: Games, anyone?
This wouldn't cause Windows users to switch, bear in mind the 98-odd percent of people who use Windows do so because they love it to bits, regardless of its faults.
They will welcome the whole "S" thing as an improvement and love it. Just like they do with telemetry and such that is included in Windows 10.
Most users love Windows, so you can pretty much place a safe bet they will not switch. Plus let's not forget that the majority of users have no idea how to install Linux.
Even those Windows users here complaining about Windows 10 and Windows 10 S will soon conform to Microsoft's new standards and continue to use Windows.
Worst case they'll pay a little extra to get S removed, or hopefully they'll just carry on using S.
They'll complain sure, but that's more because people love to complain. But it doesn't mean they will leave Windows, they love it too much.
Lastly, don't forget that average joe doesn't really care about telemetry or vendor lock in's and stuff. They just want Windows because it's what they love.
So yup, regardless of S, there will not be a significant change in market share. Heck, once Windows 7 stops getting updates you'll see a huge rise in Windows 10 user numbers.