Apparently there are new systems being developed that will be installed into aircraft to maintain separation (I think ADS-B is one), without the use of ground stations. The systems do this by issuing resolution advisories to pilots, similarly to TCAS, but with a separation standard applied that is similar to those applied by ATC today (rather than the current TCAS separation, "they won't hit").
With this system, there may be a reduced need for ATC, but only if it is fitted to ALL aircraft - and that could take a while to do.
Does anyone know about any of these systems, and if they are being used anywhere yet?