The article starts from a false assumption: that the postal service must be profitable, or at least break even.
Framing the issue this way has nothing to do with what the USPS should or should not carry, or how much they should charge.
Why is that so for the postal service but not for the military, department of transportation, or most any other government agency that provides a service? Universal free mail delivery is something that the citizens of the US want -- or at least did at one time. As a government service, it's something taxpayers agree to pay for.
Now clearly the two authors of this article, management consultants, have a different view of that need. Perhaps they are ideologically inclined to expect that government services should break even or better, in which case, they ought to take on a real challenge and explain to the Pentagon how they can "save" the armed forces. Or perhaps they have a financial interest in private delivery services like FedEX and UPS, who knows? It's clear from early in the article, "Should the federal government continue to compete against the private sector?" that the authors have a sense that somehow there's money to made for UPS, FedEx, and other private delivery services if the postal service was forced to compete on the same level as them. I'm sure they wouldn't advocate for reforming USPS if they thought it would take money away from the private sector.
In any case, before people go trying to reform USPS, let's first decide if we want to continue to support the current expectation of free (for the recipient) door-to-door mail service for everyone in the country everywhere. If citizens clearly want that, then budget (and tax) for it, and shut up about billion dollar "losses" that pale compared to the "losses" racked up by other services we expect as a modern nation. On the other hand, if the country decides that hey, we don't need to deliver everywhere any more, then go ahead, revamp the postal service to be just another profit-motivated competitor.