In an ideal world, yes, but ECL must currently stick to an environment (C) which does not allow for dynamic recompilation (no clang embedded yet).
A bit off-topic, but have you ever tried compiling ECL with TCC? That seems to be the best C compiler for use as a linkable library, but it only has machine code generators for a few platforms.
It seems that not having a compiler around is a not unusual property for Common Lisp deployment (ECL, Parenscript, Thinlisp, commercial implementations, older implementations) and is something that the ANSI standard is IMO too strict in requiring.
Vladimir