I'm in favor of PLY going into stdlib with the caveat that there are some things about it that should probably be cleaned up and modernized.   For instance, the method by which it writes the cached parsing tables needs to be cleaned up.  I still think putting the LALR(1) generator code into a common library usable by both PLY/RPLY would be a useful thing to do.  That code is really hairy and non-trivial to understand without something like the Dragon book nearby (and even then it's not easy).   

So, if I were to make any kind of proposal, I would say, make a standard library module for just the LALR(1) generator code.   If the PLY interface is needed to add pycparser or cffi to the standard library, that can be added too, but as a separate module that uses the more general LALR(1) library.