Here's a tip for you arm-chair USPS consultants: it has way less to do with who gets what delivered where and when, and way more to do with Congress declaring that the USPS has to pre-fund retiree health benefits.
Eliminating this requirement would save the USPS almost three times more money annually than eliminating Saturday delivery. Congress requiring the pre-funding retiree health benefits (which is extremely rare, I believe the USPS is the only govt entity that is required to do it) is what is killing the USPS, not Granny Engelbert getting her Ladies' Home Journal every week out in Axtell.
In other Cliff Clavin-related news, if any of you want to check out a podcast on the history of the USPS, there's a good one here:
http://backstoryradio.org/shows/youve-got-mail-a-history-of-the-post-office/