An entire arsenal of weapons, equipment and processors would be needed. A SPAAG like the Gepard, or Wildcat, or LAV Blazer etc is really the last line of defense.
Certainly this sort of multi layer defense is going to be needed in the near future, we have seen groups like Hezbollah issued UAV's and technical support by the Iranian Revolutionary guard, and being attacked by a ballistic missile is becoming more and more likely as the technology is mastered by nations like the DPRK and exported to all interested parties. And of course we also need to consider everything that flies in between small UAVs and IRBMs as well.......
I might offer a somewhat heretical view of things, in the future let the zoomies take care of aerial threats using tools like AWACS and airborne lasers; airspace management, coordination and so on are made much simpler and sensors on airborne platforms have much better fields of view anyway. As long as "we" get equal access to what these sensors see, we are better served with improved SA and the zoomies get some love from us as well...(that crackling and popping noise as the zoomies burn incoming mortar shells out of the air would be nice as well)