Stevn has a lengthy essay on the analogy between operating systems’ battle for the desktop and the schism between Christian Orthodox and Proestant sects. In a nutshell, Linux is Protestanism, and it’s very non-centralized nature is what keeps it from ataing critical mass on the desktop. It’s a fascinating analogy and one that might I might well apply in reverse to Islam at some later date (elsewhere).
One thing I note, is that Protestanism is dominant in Christianity, at least in Europe and the United States. It’s mostly in the third world that Catholicism is ascendant, especially Southern America. What does that mean for Linux? One thought is that even tough there is no common unifying distro, enough “turnkey” distros may arise that the majority of computer users one day are using Linux in some fashion.
Ultimately, I think the real barier to entry is not the OS but the applications. The primary obstacle facing Linux is really the lack of a serious contender to Micosoft Office, though now that MS has adopted an XML standard that may well change. Hardware periperals are another factor – once anyone can plug any mouse or USB thumbdrive bought off NewEgg or Amazon into Linux and It Just Works, Linux’ fortune will markedly improve.
It’s not about installing an OS – it’s about using it. To that end I don’t think that there’s really a two-year window as ESR suggests. If the various linux factions can unite, not on a distro but rather on a API or plug and play infrastructure, then Linux doesn’t need unity. It can win by sheer dint of numbers alone.