I tend to wonder if we'll ever see the day when you can't get a complete C=64; it seems like everybody and their brother is ripping the SID chip out, and discarding the rest. I keep thinking I need to find myself a C=64 system while I still can have one with its audio system intact...
Another thing I wonder: Didn't the Sega Genesis (or the Nintendo) have a separate sound chip (I believe the Sega used a Yamaha chip)? I wonder why (almost?) nobody is hacking those?