The technology and much of the hardware that could be used for upgrading the ATC network already exists. It's really more a question of getting Congress and the White House to sign off on paying for the upgrades (which won't be cheap) and whether anyone in Washington has the intestinal fortitude to actually commit to the upgrade process and deal with any disruptions to commercial air traffic (not to mention any other potential headaches) that the upgrade process is likely to cause; that has caused some inside the Beltway (including many folks within the FAA) to take a "it ain't broke, so why fix it?" attitude even though there's widespread agreement that upgrades are badly needed. As with PTC, there's a lot more to the story than what the media and Washington are telling us (and much of that isn't always accurate or truthful, either).