Before the FAA gave up, costs had tripled. And there was little or no progress over the 10 years. Now the government agency is trying to improve the system a little at a time. Canada, with similar air traffic problems, solved them by setting up a private company. It's funded and run by users, primarily the airlines.
Government still regulates airline safety.
The airlines would have a financial inventive to make a privatized system safe and effective. If the public perceives it's not safe, few would fly, ruining the carriers' business. An effective system would save airlines money. Delays today cost them billions of dollars annually. But privatization is a hard sell.