Linux is on the desktop. Many people use it as their every day operating system (I’m using it right now) or every other day operating system. Linux has more mind share now than it ever has. In that regard, it can be considered to be successful. It may not have a lot of market penetration, but it has a lot more than, say, BeOS ever had.
You have to take history into account here. Apple and Microsoft were there at the beginning of the home computer revolution. Apple, of course, had their relatively low priced Apple ][ micro-computer that was very popular. Popular enough, in fact, that they were the leader in having computers in schools across the country. Microsoft became big licensing their (really, it was “his” at this point in time) BASIC everywhere; long before Windows, long before Word. You could find Microsoft BASIC in Commodore computers, MSX computers, and a host of others. You could even buy it on disk for the Atari computers (8-bit).
Originally you were swimming against is familiarity, not comfort. Kids went to school, took a computer class using an Apple. When parents finally broke down and bought a computer, it was what the kid was familiar with. When that kid grew up he generally stuck with Apple.
Then business’ started getting computers. Jane worked on an IBM PC, she became familiar with it, and when she plunked down the astronomical amount of money to buy one she bought what she was familiar with. Jane got married, had kids, and as those kids got older they grew up with an IBM PC (now with a Turbo button!) or a compatible. Unless Jane worked for a magazine, then she probably used an Apple Macintosh because they were somewhat cheap desktop publishing solutions.
Logic isn’t necessarily a driving force. After all, at one point in time you had a choice of:
a) expensive, black & white, rudimentary sound, looked like a toaster (Macintosh)
b) super-expensive, went ‘beep’, colors ranged from green on black to amber on black to color (cyan, red, yellow, green, black) (this is not including add-on video ($$) or sound ($$)) (IBM PC)
c) cheap, lots of colors, good sound (Atari ST)
d) price range between ST and Mac, excellent color, excellent sound (Amiga)
Yet, the IBM PC compatible ended up being king.
Linux can be successful on the desktop, it all starts with familiarity. Ubuntu (or Kubuntu) made installing and maintaining Linux an easy start. If more people keep using it then it may make traction into other places. Maybe your kids will continue to use it, own their own business, and make it the de facto OS which may get their own employees to switch over.
But it won’t make a difference because desktops are dead. Computers, on a whole, are dead. They’re just shuffling around like zombies waiting to fall. There’s no differences to make things interesting (Mr Apple down the street is running, essentially, the same hardware I am – no more Motorola 68K, no more Power PC). There’s no excitement, no thrill, no innovation. That all belongs to the cellular phones and ‘pads’. And in that place, Linux has already made quite a bit of headway.