Yup, that's the plan:
* VHD I already have converted: https://github.com/vasi/macemu/tree/disk-generic
* Bin/cue is more complicated, because it supports extra functions. I also have never gotten the existing bin/cue support to work on any bin/cue files I can find or produce—this makes it hard to test changes! Do you have bin/cue files that are verified to work? 
* I'm not sure that it makes sense to turn cdrom and floppy into generic disks like this.
* Other disk types would fit in this framework fine, though: virtual formats like vmdk, vdi and qcow; compressed formats that are amenable to random access like lzo or xz; other Apple formats like dmg or sparseimage. Are there any types you'd like to see implemented?

The interface needs to change a bit, though. Right now, a disk_factory() can only return success or failure. We should distinguish "I don't recognize this disk" from "I recognize this disk, but can't open it". That way, if we find a sparsebundle, but have some mysterious error opening it, SS will not try to open it as a raw image.