Syd Lexia wrote:

The system that became the Playstation was originally designed as a peripheral for the SNES, not unlike the Sega CD. Nintendo saw the lukewarm reaction that Sega CD got and backed out of their deal with Sony, rightfully so I might add. If Nintendo hadn't backed out of their deal, the SNES CD peripheral would have quickly come and gone, and that would have been the end of it. One might argue that we would STILL be using cartridges today instead of CDs, since the PSX was the first truly successful CD-based system.

I'm sure Sega still would have designed the Saturn for optical media even if Sony never developed the PlayStation. Nintendo would have been forced to switch to discs eventually as well. Their proprietary GCN discs pretty much made all the advantages of cartridges, namely short data access times and piracy deterance, obselete.