I just got a private response about the proposal from Atsuo Ishimoto, Japan. They use two different encoding in day-to-day life (one for windows, one for unix) and have their complete tool chain setup to auto-convert all files between the two environments.
Recognizing the magic comment would pose a problem for them, since their tools assume conversion to the PC's locale setting.
He proposed to make the interpreters default encoding the default for source files which don't specify an encoding. That is ASCII on all standard Python installations and different encodings on tweaked installations.
He also told me that they put raw Shift-JIS and EUC-JP into Python literal strings -- just like Europeans do with Latin-1.
Wouldn't his suggestion be a good compromise for phase 2 ?
-- Marc-Andre Lemburg CEO eGenix.com Software GmbH