OK, here's a shallow reply to get things started...I know absolutely nothing about programming (in "computer" language), software development, etc. so it is difficult for me to comment on the possibility of "pseudosampling" on the XP-80. To do what you mentioned, wouldn't there have to be extensive OS revisions? Then, would there be sufficient processing power left for the 80 to do everything else it does (well)? If you meant being able to sample audio onto an 8 mb exp board, all 80's would have to be fitted with input jacks and the proper connections between these and the "guts" (motherboard, expansion board, or whatever) of the synth would have to be made. If you meant just loading audio files from floppy to the 8 mb board, I guess the reprogramming I mentioned earlier would have to make the XP-80 able to read various audio file types. Maybe I just don't understand exactly what you are saying, though!
I'm hoping that Roland will, at least, release something like an "XVS-76" or an "XPV-80": a 76 key workstation with the ability to read Akai, Roland and .wav files like the new XV synths are reported to be able to do. It would be better to have something like a 76 key XV synth with the XP/MC-80 sequencer and a good sampler all on board for my purposes.