Side note that has been lost to history. >From 1987-1990 I worked at Mizar Digital Systems, which built STD bus boards and VMEbus boards. Its new president who came in in 1988 I think, Joe Rammunni, decided that the STD bus was a dying technology, and looked into NuBus. As I understood at the time, he went and talked to various PC manufacturers to try to get them to adopt the standard as well, for their next round of upgrades from ISA.
Nothing came of this. Without the unified market there wasn't any incentive for Mizar to get into the business. But just imagine what the tech world would have looked like with interchangeable cards for PCs and Apples. The only remnant of this effort are my vague personal recollections and a "NuBus on board" fridge magnet which I retain to this day. mcl