> As long as they don't watch Netflix.
Fair point, for now. But Chromebooks can access Netflix, so there's no reason why this can't be extended to Chrome on Linux in the near future.
> Or play games.
Steam for Linux and Steam OS (which is a Linux distro) will change this. Already pretty much every upcoming indie game is being developed for Linux in addition to other platforms, and there's already a substantial library of games.
> Or have any unsupported peripherals.
Very few of those exist nowadays.
> Or want to use any commercial consumer software.
And what 'commercial' consumer software are you talking about? Most software nowadays can be accessed through the browser, quite a bit is spreading to Linux, or there's an acceptable free substitute. Don't tell me a free office suite with Linux isn't compelling to the average consumer, especially now that sending documents as PDF is more socially acceptable than sending Word files...
I mean, I use Ubuntu exclusively, all native apps, while attending University, developing pet projects, and doing normal 'computer' things like using Skype, playing games, etc... I recently bough a Fujifilm X-A1 camera (great device BTW), and GIMP even works great for importing and developing RAW files...
I don't see what more the 'average' consumer needs - and don't say MS Office or Photoshop, because the vast majority of people don't 'need' them...