I have been going back and forth over being happy for this news and being frustrated by it...
...happy because at last it is a pack-in that makes absolute sense, and is something I have lobbied for in the past...
...frustrated because it has been quite some time since I have bought all the figures in a single wave, let alone 30 figures over multiple waves...
...hopefully it will be a prequel droid like the spider droid, so I don't have to worry about how I'm gonna get all the pieces. In fact calling them "Droid Factory" waves would point to the "one big droid" being the big droid in the factory in Episode II that has already been mentioned. Might even tie in with Clone Wars, since it's in that era. If that's the case, I'll take what parts I get as droid junk pieces and actually be pretty happy for it.
If it turns out to be an OT droid I just gotta have (Probe Droid is really the only thing that might remotely fit the bill, but those would be thirty small pieces. Like, halves of arms or claws or antennas or what not.) then I'll have to weigh the costs of buying all the figures and trying to sell/trade the ones I don't want away, or trying to trade for or buy needed droid parts.
I guess in the end it is a happy dilemma. Can't wait to find out more about it!
I saw this thread and all I could think of was the vintage droid factory. 
Me too...I was actually hoping they were gonna make a modern version with some buildable Sandcrawler Droids. I still think it would be a huge seller!!