I absolutely agree with you about the penchant, but I know first hand from Microsoft employees that the backwards compatibility issue is a complete pain in the

I absolutely agree with you about the penchant, but I know first hand from Microsoft employees that the backwards compatibility issue is a complete pain in the arse. Supporting ARM on managed only paves the way to ditch unmanaged code in x86_64 in the future. Supporting native unmanaged code might require a recompile and some testing, but might be possible (given the Xbox 360) but then you're going to have trouble with x86_64 only references in your code. Implementing some sort of x86 -> ARM is going to be a nightmare of epic proportions, Rosetta-type technologies be damned.