I realise I’m very late to this discussion, but scanning through the PEP, there are a couple of deprecations I was (mildly) surprised to see:
cgi: Yes, launching a new process for every request is inefficient, but there are cases where it’s good enough. It’s conceptually much easier than writing an application with a proper web framework - it’s the web equivalent of scripting. And there are (or used to be?) cheap web hosts would give you CGI support as the only way to run custom code on the server, and certainly don’t make it easy to install something from PyPI.
Reading bits of the previous discussion and making educated guesses, I think it will still be possible to write CGI scripts using only the standard library even without the cgi module, but I’m not 100% sure. If that is right, maybe it’s worth spelling it out in the PEP?
telnetlib: Telnet is old hat, but still used at times for devices on a local network. I ran into it when playing with an old e-reader: you could enable a telnet server to get shell access. A quick look on PyPI turns up two different packages to control VLC over telnet, packages for controlling network devices and other things, and a package adding SOCKS proxy support. These are all using telnetlib and released in the last couple of years.
There’s probably no particular reason this needs to be in the standard library, and I see there are already several alternatives on PyPI (telnetlib3 appears to have the most attention of the ones I found). Maybe the PEP can explain this - the current detail gives no rationale for removing the module, and its brevity implies that telnet is self-evidently useless, which doesn’t seem right.