The destruction of certain kinds of buildings on the AI side, like perhaps supply trains or whatever else, could cause immediate drops of X amount of currency.
Hello Astro Trains! 
(Even more interesting if successfully completing a run gives the destination system a bonus or uses some of the currency there, making it very advantageous to reroute and sabtoage cargo cars on trains, rather than just ignoring them.)
That would be an awesome suggestion to note down in the astro trains section, actually! The astro trains discussion last week was one of the things that helped spark the idea about reinforcement currency being more granular like this, too. There were several discussions that people had about that, more ways to damage the AI in specific fashions, etc, that really led into this.
ATM, this sounds awesome to me. It replaces a fiddly thing (Barracks) with something cleaner, provides a performance boost by effectively not having to acknowledge all those idle ships exist outside of an Int32, and it'll probably look really cool when you wake the planet up and ships start pouring out of the bays, Hollywood alien mothership style.
Bonus points if the AI wakes up a whole whack of them at once to pool into a CPA.
I imagine that for CPAs we will do something along the lines of these, or have some sort of motherships or something that are used with ship bays on them so that they show up and it's attacking your planets rather than your framerate quite so much.
I think we can make these visually look really cool, too, even just when they're parked there.
