They can put almost all those folks on a rural route. There will be a lot of route realignments over the next few years as all these useless post offices are closed. My study (done in the 1970s) said they could eliminate all but about 1200 of them ~
It's an urban area, but there are several post offices within a mile of downtown. It would probably make sense for the private sector to supply post boxes. It really isn't necessary to have a full blown post office when all that's really needed are store fronts with PO boxes. The USPS made a big stink when private companies started trying to provide mail boxes, and they wouldn't let them be called PO boxes in their addresses. They are called Private Mail Boxes (PMB). This foolishness should be ended.