If JS ever gets finalizers we could probably consider the total feature set JS has at that point sufficient for the implementation of most other dynamic languag

If JS ever gets finalizers we could probably consider the total feature set JS has at that point sufficient for the implementation of most other dynamic languages without resorting to writing a VM in js or using asm.js to embed a full C runtime using arraymaps for a heap. At that point we'd probably see some subset of JS devolve to a bytecode, I'll bet.