Other countries (Denmark is an example) have completely privatized physical mail delivery. All official mail is electronic. There's some nostalgia for the postman on his red bicycle (or in the USA, walking the neighborhood or driving their funny looking trucks) but are they really necessary?
Edit to add: since running post offices is explicitly a Federal power, a conversion of US Mail to being electronically based would be completely within scope. There would be no arguing over "states rights" that tends to become a logjam for any other national infrastructure or policy changes.