In theory, drives like this could be supported in the future, but that is up to drive manufactures on whether or not they would like to allow 3rd party apps like Infuse to interact with their products.
In a nutshell, any storage devices that connects via Lightning is part of Apple’s MFi program, which requires certification, device specific SDK, and explicit permission from the manufacturer. SanDisk is one of the few companies I know of who has opened up their program to 3rd parties, as generally most manufactures simply make their own app and direct users to use this.
With regard to the WD drives, either of them could work with some 4K content, but this of course may vary based on network conditions.
Hope this helps.