Our military manufacturing volume was not very high before WW2. It wasn't until the potential adversaries became actual adversaries that we ramped it up.
If a similar sort of nation-uniting threat arose, to the extent that we'd be willing to take extreme measures like halting all manufacturing of civilian automobiles, drone production could be massively increased.
Of course, the problem is that the willingness is unlikely to be there until a serious war breaks out, and then we may not have the luxury of taking a couple of years to ramp up.
