As I understand it, any app can store data on the SD as long as 1) it's not program data and 2) it specifically has ownership to that folder (although the app has to be programmed to do so). So Pocket Cloud (which was updated for KitKat) can store podcasts on the SD card, but not program files.
Pictures and video can be saved directly to the SD card, but 3rd party apps can't save to the DCIM folder. Picture editing apps will need their own folder to save edits and can't be saved back to the DCIM folder either.
I can live with all of that, but the biggest pain will be copying files over the network to the SD card. The transfer app will only be able to copy to a specific folder and not a generic video folder, but only if the developer updates the app to create exclusive folders.
On a file storage level, it won't change much other than on an organizational level assuming the devs update their apps. But the big thing that's lost is if you wanted to move, say, 60mb of program data to the SD card. That won't be allowed anymore without root.
Again, that's how I understood Jerry's article. Feel free to correct me where I'm wrong.