But I don’t know how hard it actually is to gun down a drone

For an attack helicopter with a turret, trivial especially if automated targetting assistance is integrated.

I fear theory vs reality in this one. If a couple helicopter pilots are trying to save a city, they may not have the bandwidth to deal with all th drones in the airspace at once and get too close, even with vastly superior technology.

To be clear I think the future is helicopters + drones not one or the other so the question to me this scenario poses is why didn’t the helicopters have a screen of protecting cheap loiter/surveillance drones or interceptors already in the air waiting?

I am sure this kind of thing will eventually happen, I just doubt it will be broadly effective.