I suspect it will be more subtle even if it's only battery life limited. Huge swarms will also struggle against fixed defences. More likely it will be used in ambush. E.g. air deployed near an enemy convoy, or swarming from rooftops and windows onto an infantry unit. Counter deployment will have to be seconds to stop the lead elements. Potentially with heavier reinforcements flying in.

I've personally got visions of a Boston dynamics dogbot with a harness full of drones. 1 button press and a few dozen micro drones swarm out, with larger ones launching as needed.

I could also see facial recognition drones being deployed from a predator drone, like cluster bombs. A little akin to the bots used in the film minority report. They swarm a building or block, and try and identify all the faces they can find.

The key thing however will be battery life. Multicopters are power hogs. You need around 40% battery to get maybe 5-20 minutes flight times (depending on how the manoeuvre). Longer times can be achieved , but requires larger systems with higher costs. Is 1 system with a 2 hour flight time worth 20 smaller systems only good for 10 minutes?