A couple of high level questions:

a. How do folks feel about providing a new "text" parameter to replace the cryptic "universal_newlines=True" that would explicitly be equivalent to "universal newlines with sys.getdefaultencoding()"?

b. Given (a), what if the new "text" parameter also accepted a new "subprocess.TextConfig" object in addition to the base behaviour of doing a plain bool(text) check to activate the defaults?

One of the biggest problems we have with subprocess.Popen is that it still attempts to use a flat configuration model for a complex operation involving 4-7 underlying elements (starting the subprocess, configuring stdin, configuring stdout, configuring stderr, and potentially local counterparts for stdin/stdout/stderr if pipes are used), and that situations unlikely to ever improve unless we start introducing some hierarchical elements to the configuration that better mirror the structure of the underlying system capabilities.