ProM
you're possibly correct, however you would need to have far more regimented airspace to start with... automation will work with simple airspace but it will bring with it a much less efficient operation especially in and around busy TMAs.
You'd also need a human element present for any emergencies etc. Automated ATC might be possible in the future, but it won't replace ATCOs in this century.
Pilotless pasenger jets is more readily achievable (like, right now), however the flying public would in all likelihood be the biggest hurdle to that happening.