This is an interesting development. One can argue that the Canon engineers pretty much knew that the camera was capable of 24p with the higher (1000x) cards, as it's not like the flash memory manufacturers aren't testing their products with all of the various camera companies prior to their release. The 1000x cards have been out for a year and a half now, so it's safe to say that Canon engineers knew full well that the MKIII was capable of RAW recording using (the fastest) CF cards.
That said, RAW video isn't something Canon has dabbled in extensively at that prosumer level and price point. So even though the feature was obviously workable, it may not have been guaranteed/developed in time for the camera's release. Canon can't deliver a camera worldwide and advertise such an important feature and have it cause their cameras to crash/overheat because they didn't have time to test it out.
As for this news trouncing BMCC/BMPC/BMCC4K? Meh. The hack, I'm certain, is welcome for those that already own the camera, but really, unless you already own a ton of Canon glass, the MKIII isn't a "must buy" now that it has 1080p RAW via a hacked firmware update. The BMPC camera pretty much equals the apparent quality of new haxored MKIII at three times less the price. Granted you don't get full frame, but if you really need FF, then feel free to pay three times the price. It IS a bargain if you need FF-RAW.
Regardless, this is good news. Hopefully Canon will embrace this, and release their own firmware update instead of trying to pretend the same people that can afford the MKIII are the same people that can afford their c100/c300 pro line. The CF card costs are actually reasonable if you're getting RAW FF for the price of a really good CF card. Another good plus of getting a 1000x card is that they dump to storage -really- fast.
Now all Magic Lantern has to do to REALLY shake things up is offer 1080p RAW on the T4i/T5i. :)