+1
A new Sound card for all AMIGAs (inserted on PAULA?): 4 to 128 channels! 
I wonder if Paula, or a Paula-derivative, is the best model for a future sound card for classic Amigas?
If it was a good model, and capabilities were easily extended (more channels, higher bitrates, deeper sample depths, etc), then I guess an FPGA would be the best route. Which makes me wonder about a generic FPGA card for the Amiga, one that could be programmed on the fly (by the host Amiga even) to become whatever hardware you wanted it to be, whether that's a 16 channel Paula, or a simple RTG card, or a mixture. I/Os would be an issue - to be a sound card you need audio outputs, to be a video card you need a VGA/HDMI output, to be a USB card you want USB outputs...