According to Robbie Bach (who was head of Xbox at the time of the 360's BC initiative), the way they avoided paying Nvidia was through the downloaded profile packs. That's why BC games came in chunks, rather than all at once. They had to create a special profile for each game that was going to be BC. And that required the participation of the individual publishers. It's also why it was only a limited selection of games and why some could never be added. The only way around this would be to emulate the machine itself. I was hoping they would do that with Scorpio, but they're obviously sticking with the "profiles" model. I bet fewer than 50 OG Xbox games are ever made BC for the Xbox One X.