Intel killed off their ARM (XScale) for Atom...
PowerPC owns gaming. MIPS seems to still be common in networking devices. ARM is mobile and the rest is Intel and noise.
Seems to me that the killer feature ARM has isn't technical at all, it's that you can buy a core, graft on a DSP if your core doesn't have one (OMAPs already do) and your secret sauce needs a DSP (half the phone vendors have their own audio enhancement stuff or echo cancellation code that they think makes the difference) graft on a mobile chip and fab your own part. Then you add memory, flash, a battery and you've pretty much got a phone.
I'm not aware of any medium volume products that use custom Intel based hardware, I have no idea what the costs or terms are but I'm under the impression that unless you're going to make 5million chips, it's just not worth it with Intel parts. Now say intel opensourced an SSE echo killer and built some kind of 2watt Atom with GSM built in style chipset and it cost $15, I bet you'd start thinking ARM was in trouble.
Intel can pretty much build the highest performing per dollar chips, they can build them cheaper than anyone else, they have much more reliable processes than anyone else and they've shown time and time again that when they put their mind to it they can compete with anyone else.
I'd need to see some really compelling evidence that ARM was moving in to the serving market in any meaningful way. I thought they had a match with PowerPC, thought so with AMD, thought Linux was going to make alternative platforms viable, and probably thought they were in trouble several other times but they are fiendishly good.