If you're looking for evidence why Windows RT won't be around for the long haul, just take a look at Microsoft's new Surface 2 tablet. It highlights everything wrong with RT, and points the way towards the operating system's eventual demise.
The Windows RT-based Surface 2 offers modest improvements over the original Surface, including a Tegra 4 1.7 gigahertz quad-core ARM chip that Microsoft says makes it 60% faster than the Surface RT's processor. There's also an improved screen, Dolby Digital sound, better cameras, and a better kickstand.
That's well and good. But the Surface 2 is still stuck not being able to run Desktop applications, because it's based on Windows RT, not Windows 8.1. So Surface 2 owners are limited to Microsoft's still-limited Windows 8 and Windows RT app ecosystm.