Ok, honestly... how hard would it really be to put together a SIMPLE consumer OS?
Basically you need a browser, a media player and library and a file browser.
From there you *might* throw in a simple drawing program, text editor, calculator and a few other widgets.
The key is to simplify everything. Throw out all the extra bells and whistles, hire some good UI designers.
I personally don't think this is rocket science and most of these components are out there already just waiting to be put together. You could probably pull this off with a team of 100-200 programmers.
As for the hardware... these guys are already hardware manufacturers and know how to put together a machine. So, factor that part out.
The problem with Linux, to be honest, is that people want it to support whatever crappy computer they already own. Dell, HP or whoever could easily produce standardized systems that they have optimizied drivers for and that are fully tested. No need to support 800 different wifi cards, video drivers, disk controllers and other nonsense.
Let's be clear: Dell and HP could put this in motion of they had vision and balls. This wouldn't even have to be that significant of an investment on their part to get started. Look at how quickly Apple took BSD and whipped up OS X.
I own a mac and use OS X every day as my main computer. Let me tell you, it's buggy, single threaded and sometimes just annoying to use. Apple does a lot of things that are either just backwards or braindead. Everything else is just eyecandy.