How can nim generate AngelScript code?
If someone forks the Nim compiler and adds that backend. (Or pays someone else to do it.) Nim's core devs need to focus on much more important things.
Given that AngelScript is a very obscure target (compared to say JVM, CLR.NET, LuaJIT, BEAM, Go, direct WebAssembly, etc), I think the odds of that are infinitesimal.