How will radar systems be used in FAA's NextGen ATC plans? Based on the reading I've been doing of FAA's Next Generation Air Traffic Control (NextGen) plans, I've been wondering if and how radar systems will continue to be used for ATC as NextGen rolls out?

Questions include:


Is it correct to assert that radar coverage will effectively become a less precise, backup only, data feed? I am suggesting this because my understanding (which could easily be incorrect) is that ADS-B will mandated for most (everyone?) and so aircraft will be actively reporting their precise position without the need for a radar track.
Will existing radar coverage eventually be phased out?  Seems unlikely due to airspace security issues alone. But are there any other reasons to keep radar coverage?
Under the ADS-B rule of the FAA aircraft operating in Classes A, B, and C airspace, as well as certain other specified classes of airspace
within the U.S. National Airspace System are required to operate ADS-B Out avionics. 

This means that these aircraft can be tracked without the use of radar. These ADS-B tracks will be more accurate than radar tracks and have a higher update rate. However for reasons of integrity, continuity of service and security, radar will continue to provide coverage. Currently a lot of airspace is covered by multiple radar layers, the introduction of ADS-B allows for a reduction in redundant radar coverage.

Aircraft not equipped with ADS-B (operating outside of class A,B, or C airspace) will be tracked using radar. The radar tracks will be broadcast on TIS-B (Traffic Information Service - Broadcast) so that aircraft with ADS-B In receivers detect these aircraft as well.