Can’t really privatize it as the Constitution stipulates that it’s a function of the US Federal government.
The persons who put it in the Constitution would be blown away if they could see the technological advancements that have turned it into an anachronism.
The Feds could always retain a much smaller service exclusively for government mail or even ‘sensitive’ government mail- IRS etc.
Bail it out only until 2013, then cease post office activity for non-government mail.