While thinking about asking on G+ for feedback, I realized that if I get this to the point of a module-level warning, it won't be a big deal. It would be just like warnings you deal with when supporting old versions of Python along with newer versions where things are now deprecated. That way  users of imp could just do::

with warnings.catch_warnings():
    warnings.simplefilter("ignore")
    import imp

and be done with it. This means still striving to deprecate every function in imp so that it can all be replaced with a single module-level deprecation is a reasonable goal to have.