The USPS is considering expanding the community mailboxes to the 'burbs as an alternative to reduced delivery days.
http://usgovinfo.about.com/b/2014/05...livery-gao.htm
If shipping costs keep on rising, Amazon might be better off, at some point, just dropping the two day guarantee and refunding the full subscription fee to the subscribers who find it unacceptable. Or buying USPS outright.
Me, I'm happy enough with no-limit free shipping; I never order stuff I can't afford to wait for.