It really wouldn't be. All the information you say we'd have in 15 years we have now. There are dozens of videos explaining exactly how to play your class exactly how to kill each boss. There are hundreds if not thousands of live streams of kills of every boss from every PoV. Even cutting edge RtWF progress is streamed now you can watch them build starts and break down second by second exactly what they do if you want to.
If they releases Crucible of Storms again in 10 years it would still not be cleared by the majority of people that tried it. Especially not in the gear it was designed for. Modern raids are far more mechanically challenging, modern classes are far more mechanically challenging. Modern wow is just a much harder game that wow used to be.