feasibility rants
Apple's guidelines for cards for PDS slots are very similar to NuBus cards, so there's actually not that much difference in developing one or the other.
With FPGAs it's not that difficult to build a card which will work regardless of which PDS slot it's plugged into. Although making it autodetect that might be a bit of a trick. It'd be nicer if the user set a jumper.
Of course, there's only one PDS slot in each machine. So a multi-function card such as IDE/USB mentioned above becomes attractive.