Intel has nothing to be worried about:
…anything that an ARM chip can do to save cost or power can also be done by an x86 chip.
The real question is whether ARM does:
Now, ARM isn’t dead yet. The iPhone uses an ARM processor because there’s no x86 processor that would work as well in that system. ARM processors will probably see at least two more generations in cell phones just because there’s so much ARM-based software out there (including all the software on the App Store).
But somewhere around 2012, we’re going to see x86 chips poking into that space. The value of instruction set compatibility with the PC market will persuade developers of new cell phone platforms to go with x86 chips, and eventually even established systems like the iPhone will switch over.