> OSes could implement the instruction decoder layer in software, transpiling binaries from a standard bitcode like WASM, JVM bytecode, LLVM intermediate code, and/or even pre-existing instruction sets like X86 and ARM to the underlying instruction set of the processor core. Each new processor core would require what amounts to a driver that would look not unlike an LLVM code generator.

We already have that; the bitcode is called "source code" and the instruction decoder is called a "compiler".