Whilst I have no doubt the Amazon freight airline could become quite large (Jeff Bezos doesn’t do things unless he can scale them up)… the other carriers will survive and thrive.
The Amazon business was important, but not critical to their operations.
Why would they? Prime air will only be good for a few cities and routes. Amazon does not have the distribution network and cannot build a distribution network with their market to pose a threat.
“The United States Postal Service does not directly own or operate any aircraft or trains, although both were formerly operated. The mail and packages are flown on airlines with which the Postal Service has a contractual agreement. The contracts change periodically. Depending on the contract, aircraft may be painted with the USPS paint scheme. Contract airlines have included: UPS, Emery Worldwide, Ryan International Airlines, FedEx Express, American Airlines, United Airlines, and Express One International.”
Basically FedEx is getting revenue via contract running stuff operated by FedEx and other companies.
I think the bigger business highlight is the story on Amazon’s side. Now they won’t be paying another company to handle a portion of their shipping. They’ll be paying themselves essentially.