I'm not an LLVM expert, but Swift is an LLVM frontend, so once it's open source, I think it should work for the various backends?

Right now the issue is library support - swiftc can already just spit out LLVM IR: https://github.com/kripken/emscripten/issues/2427

The stdlib would be included in the open source release.

Linux boxes would fulfill "non-Apple product" though. Unixy programming languages like Swift and Python have always been weird on Windows.