I really don't think ADS/B will replace radar in terminal areas. It not only relies on pilots having the squitter, it relies on the squitter being plugged into something that knows where it is. A day where the gps don't work and everybody is guessing.
Will be an excellent concept at altitude where real aircraft (that can be trusted) fly. Will be better than nothing in enroute airspace where not much flies, it might even make NAS work.
The answer for terminal areas is radar, and where you can't afford or justify a radar a multilaterator, not ADS/B. As our f@ckwit of a minister hasn't spoken to anybody besides DHS he probably doesn't even know its an option. And in the meantime, seeing he is no longer terrified about facing an election, expect a follow up to his loony directive...
