I'm sorry, this is simply not true.
Both ARM and Intel are hostages to their history.
If ARM is to produce a chip that is competitive with Intel in desktop applications, then it will need to (a) improve its performance at native multi-tasking, (b) improve its FPU, (c) develope hyperthreading, out-of-order execution, speculative branchong, (d) add support for things such as virtualisation extensions.
Can it do these things? Yes, of course it can. Can it do these things without adding complexity and transistors? No, it cannot. ARM can become compeititive with Intel in desktop, but only by becoming more like Intel. Those extra transistors? They add die size (i.e. cost), and they add drain (i.e., reduce battery life).
Now Intel, can it produce a super low power chip, running the x86 instruction set, that is usable in smartphones, etc? Yes, but if it wants to do this, it will have to shred transistors, and shredding transistors means shedding performance and features. In other words, it will no longer offer any specific performance advantages.
It is *possible* that Intel's process technology lead means that it can produce a competitve mobile chip before ARM produces a competitive laptop/desktop chip. But it's also largely a moot point. Unless there is a compelling reason for handset manufacturers to choose Intel, then it will be an irrelevent share of the market.
The same is true for Windows 8 on ARM. No legacy software support, and no meaningful cost advantage (Intel Atoms start at $20/chip, about the same as a Tegra 2.) Plus, of course, the architecture of the box around ARM (on the PC side) is not set in place yet.
Unless something very surprising happens, we will see ARM taking overall share, because smartphones and tablets are growing as a percentage of the computing market, at the expense of desktops and laptops. But it is unlikely that ARM will take a meaningful share of the PC market or Intel of the smartphone one.