So, the question to be asked is: Where shall this end.
If the scenario is indeed parcel delivery, hazard to other man made airborne equipment will be of minor interest, I postulate.
Due to the amount of traffic needed and its closenes to human settelments other issues will dominate:
- Environmental issues like noise and hazards to biological air traffic participants - large (birds) or small (insects).
- Hazard to persons and property on ground due to failure of equipment or collisions with above.
As small as the failure probability might be, the sheer amount of drones needed will make this a relevant factor.
So basically two scenarios are possible:
This will remain an application for a small niche (like the one DB pointed out) - a peaecful coexistence with GA might be possible, but better not buy stock of any startup.
This shall become a replacement for the white, yellow and brown vans - for noise and environmental protection these things must fly much higher and GA traffic will be displaced from lower airspace.
So we GA pilots must fight it.