PPC isn't dead of course, IBM's latest Power7 development looks like a pretty potent processor. If it can deliver hardware clustering it'll be quite the thing for your home super computer.
But what will the chip cost and how much to put it into a motherboard and how much can OS 4 really use the multi-core features/clustering? And what advantage would this give a home user?
Really the problem is that the market has matured since 1985. In '85 there was little software, computers in homes were unusual, mobile phones were 1G brick that had sparse coverage. People used film cameras, records were the way to sell music, CDs were expensive and somewhat rare. People still had music on tape! Computers came with floppy drives and floppy drives actually had some use. TV was analogue. Domain names were brand new, people often used bang paths. It was a different time.