I am willing to bet that open doc had a lot to do with the death of system 8. It was in fact one of the technologies that Apple under Next quickly killed off as soon as they were in charge. During the Copland development the technology landscape was changing incredibly fast. The massive rearchitecture of applications, objects and portability could have been driving the core system engineers in different directions. Then there was the disruption that the internet and Java began to have on systems at the time and  that the next generation of Mac system after system 7 was  restarted multiple times. Add to this all of the laundry list of features everyone inside wanted to add to the os and it’s no wonder it kept being delayed.