[createdapril24]

In theory, sure, but those swarm shows are pre-programmed: they aren't reacting dynamically to a (chaotic) situation on the ground and they aren't communicating with operators.

There's some far-flung future in which drones are fully autonomous and in fact don't even need antennas. At that point it's possible they can be massed. But it's a bit of a science fiction. At least, there isn't any such product available (commercial or military) and this isn't how drones are being used in war.

For economies of scale - true also of artillery and other equipment! The more you can scale production the more cost-effective the weapon. As mentioned, drones in the Russo-Ukraine war are starting to see their cost-effectiveness wane due to having to become larger (larger munitions, large antennas, etc), heaver (bigger batteries, larger munitions, etc), and non-disposable (high cost frequency hopping gear, difficult to find munitions, difficult to source batteries, etc).

Giant technological leaps could happen, but it's nerve wracking to bet the outcome of a war on something like that.