Here is Grant Petty with a full rundown of everything the company is announcing at IBC (skip to 22:30 for a demonstration of Fusion, software which is made by eyeon):

Obviously there is a specific market for PL versions of these cameras, especially since the Cinema Camera's passive MFT mount already allowed adapting to PL. A native PL mount should have no back focus issues, and as Grant says above, with the way the camera is designed, the native PL mount should be able to handle very heavy lenses, even without lens support. The 4K camera did not have another mount option previously, so the PL version means it should fit nicely as a B-cam to the PL mount version of the URSA.

With the addition of PL, here are the mount options for the Cinema Camera and Production Camera 4K:

Blackmagic Cinema Camera Production 4K Mount Options

What would have been interesting is for Blackmagic to have created an interchangeable mount system for these cameras early on, which would have negated the need for so many different versions. Wooden Camera makes a modification to the 4K camera that adds RED's interchangeable mount system, though the best of all worlds would be one made by Blackmagic that worked electronically with MFT, E-Mount, Nikon, Canon EF, and passively with PL (though I suppose it's a bit late in the game for all of those in one system).

As a recap, here are the major announcements and additions today:

What could actually end up being the biggest news of the day is the acquisition of eyeon Software, which makes the compositing application Fusion. By buying eyeon, Blackmagic looks like they are slowly but surely taking over the high-end post-production world. Their path looks very similar to the way Apple acquired Color and Shake back in the day, and looked to be conquering post until they changed focus and completely redesigned Final Cut, killing off a number of these separate programs. 

It will be interesting to see how Blackmagic packages the software from eyeon. Fusion would probably stay a separate program for now, and if it does, I see it getting Mac support, as well as better integration with Resolve. It's even possible we may one day see Resolve and Fusion combine into one application similar to Smoke. Either way, Blackmagic has taken one giant leap into the VFX world.

Source: Blackmagic Design