Agree, most impressive, and I expect to see more of this sort of rescue.
It must be remembered that in this case, that the two swimmers were conscious and able to save them selves with the aid of a float dropped by the drone.

We are some way away from a drone being able to save the unconscious or injured victim.

Here in the UK, tests have been carried out using drones not directly to rescue, but to locate persons in trouble in the water. The lifeboat may then proceed directly to the casualty rather than having to search for them.

I also expect to see more use of drones for accidents on land, both to locate victims and to drop supplies.
If a hiker or walker is lost or injured and suffering from dehydration, a litre of water dropped by drone could preserve life whilst rescue is arranged.
Likewise in cold conditions, a blanket and a couple of chemical hand warmers could preserve life.