Surface RT and Surface Pro are slightly different beasts. Why Microsoft made the decision to use ARM chips in the first Surface and the Surface RT is beyond me. It was a stupid mistake and the two systems are likely to die quickly because of it.
Eh, I tend to disagree. iOS and Android devices almost exclusively run ARM chips, so does your smartphone, the PS Vita and PS TV, and all gameboys since the GBA. The ARM chip isn't the problem, its a perception/expectation that a "windows" OS ought to run all the "(other) windows" software. No one balks that the iPad doesn't run OSX software when its really the same deal -- why? because no one had that expectation and OSX just isn't popular enough in the mainstream for people to care about running its apps everywhere. Ironically, OSX apps by their nature are actually a lot closer to their would-be iOS versions than legacy windows desktop apps are to their Windows Store app versions in many respects.
The negative perception of Windows on ARM chips is, ironically, fueled mainly by the success of traditional windows -- people care enough about their "(other) windows" software that they want to run it on "windows" everywhere. Frankly, In a perfect world, I don't even think Redmond would want the semi-weird hybrid of mobile and desktop apps that is Windows 8/8.1 on a traditional PC. But it was really the only card they had to play coming so late to the tablet party and needing to establish a user base for a tablet-friendly app model. In 2-3 more years of "modern" Windows addoption, there will be more devices capable of running Windows Store apps than there will iOS or Android apps -- guaranteed. The Surface and Surface RT need apps to succeed, they'll get there by sharing the load with modern windows running on x86. Surface and Surface RT are a long road perhaps, but had Redmond tried to tackle tablets with a distinct split between legacy Windows and Windows Store (formerly Metro), windows store would be a guaranteed failure.
I think the mistake they've made, and continue to make, is pricing the Surface and Surface RT so high. They really need to be $50-$100 less than they are. I also think there should be an 8" ARM-based surface (for around $250), and a low-powered x86 surface (with an atom/jaguar-style processor) that's should be, say, $500-$600 to fill in the new gap between Surface Pro 2 and Surface. Then they'd have low and high-end devices for both real productivity and entertainment. While I'm making wishes, I'd love to see a real ultra-book with Surface design language, build-quality, and even longer battery life than the Surface Pro 2.