It's no different than what happened to Red. Red knew they were going to get fierce competition from new Sony cameras and so they had to react quickly which definitely caused a lot of Red users to get pissed that their investments tuck a nose dive.
With Black Magic for example, you can get a $1,000 pocket version and a $4,000 4K version with a Global chip. I guess they feared that their original camera was too close in price to the 4K version. As for another theory, since the pocket camera has an electronic M43 mount, people are not going to be surprised if the original cameras also get an electronic mount. This way, they can release an electronic M43 mount version for a little more. Their are a lot of people who'd be willing to pay an extra $50 0- $1,000 for an electronic mount (depending on when it gets released). Lenses such as the Panasonic 12-35mm, 20mm and the Olympus 12mm would be perfect for the 2.5K camera. As for a third theory, it could have been originally planned a while ago which might have been similar to what Panasonic planned with the GH3. Basically the GH3 was hard to get for a very long time in the US since people kept buying every single unit Panasonic was able to produce. The price has stayed the same for a while and then not long after the camera finally became easily available, that retailers started lowering the price. As for a theory about fearing the 5D Mark 3 hack that's been mentioned elsewhere, I really don't think the price drop had anything at all to do with that camera.