AMD and ARM's new CPU/GPU virtual ISA 15 years ago
Think of it this way. OpenCL like OpenGL is an API that says you can build it however you want so long as it comply's with this standard. DirectX and DirectCompute are the same. Despite their vast architectural difference both AMD and nVidia GPU's work on them just fine, All FSAIL does is bring it all closer to the metal and encompasses the CPU as well, (instead of just GPU alone). You're telling me Microsoft (still OS marketshare leader) want's to split arch dev teams between x86,ARM or whatever else the future brings. They'll probably come up with their own version of FSAIL but I think they'd be stupid if they weren't on board (at least with their own version).