I've been giving this some thought recently and discussing it with more rational people than those that inhabit this forum. Modern society is beginning to form a habit of abandoning old systems completely. I'm sure this is partially to do with the geometrically increasing pace of technology. If there's a new, better, faster, more efficient system, why maintain the old one, right?
Sometimes I wonder though if we aren't kicking out our legs from underneath ourselves when we do that. Sure, we've got new hover chairs so we won't fall. But what happens when the hover chair fails? The USPS is a good example, as is the POTS system. Yes, we could eliminate the USPS and save money. Let private enterprise handle first class mail, they might be able to do a better job. More and more people are going to wireless phones exclusively. It's conceivable that someday the old POTS system could be retired completely.
But what's our fallback when new systems fail? As you are well aware, our current economic situation is untenable. Who knows what the straw that breaks the camels back will be, but it could happen at any time. If we've eliminated these old systems, what happens when our fragile new systems fail during a time of economic turmoil? If we eliminate the USPS, what happens when the price of oil skyrockets and private carriers raise rates and eliminate service to unprofitable areas as a result? Same with phone systems, if customers can't afford cell phones and the expansion of those system stops, maybe with towers in less profitable areas being decommissioned. If the POTS system was abandoned simply because it's "old" technology, where does that leave those who can't get other service?
Now don't take this as an endorsement of propping everything up on the taxpayers dime. It's simply an observation, and something to think about.