Which one?

First which ISA? x86(32- or 64-bit)? ARM (if so, which flavour)? MIPS? Power? RISC-V? Z80? System-Z? 8051?

Once you've selected which ISA(s), which assembler? gas? Microsoft's? NASM? YASM? fcml?

There's no single "Assembly".

I think it is already be possible; @SPQR has shown that you can use GNU bash to access the GCC compiler to compile C, so it should be trivial to compile assembly aswell