All the secrecy, all for naught.
Wouldn't surprise me if RT is scalable to support different processors, after all Android does it just fine.
Well, it did surprise everyone but the problem is executing the marketing & PR. MS didn't do enough to differentiate RT & Pro. This caused confusion among even the retailers. Don't even need to mention end-users.
It's not too late because, Snapdragon S4 is not powerful enough for RT while Snapdragon 800 probably is. Moving forward it means phones will have the power to run RT so the logical move is for RT to move to mobile platforms.
It doesn't make sense for RT on tablet because next year, Intel Atom Baytrail will be powerful enough to run Win 8 at a good speed (for most tasks) with 10-12 hours battery, while Haswell will have 7-8 hours.
Android can be "easily" port to many platform because at the end of the day, it's a mobile OS with a MUCH smaller codebase than Windows.
My guess is Android probably occupy less than 100MB on ROM & 250MB in RAM. Compare this to Win RT which occupies 10GB on ROM & uses 600-800MB on boot.
It's a lot harder to port Windows because of all the thousands of pieces & drivers. I'm not holding my breath on seeing RT on Snapdragon actually unless MS is really serious in stripping RT down to fit on a smartphone.