Last gen consoles not collectively reaching 400M as he predicted is not the point. The point was to address the ridiculous claim/lie that Microsoft actually suggested they would sell 1 billion Xbox One consoles. That never actually took place. "Journalists" horribly misquoted a Microsoft exec who was speaking about the entire games industry as a whole outside of consoles.
360, PS3 and Wii actually did come very close to that 300 million mark, so that's where his prediction the next consoles would all reach 400m together came from. And then he cited moving beyond consoles, meaning PC, mobile devices, cloud. That's where the potential billion comes in. He was never talking about xbox one gen consoles selling anywhere near such figures.
At the time he made those comments around may 2013 nobody yet knew Xbox was going to start releasing first party games on PC day and date with the console versions. None of the big 3 were doing that. Only 3rd party publishers were. Nobody knew streaming would become so prominent or that Game Pass was coming, and how that would reach into so many different potential devices, actually bringing with it next gen new console games - a lot of them - in a way that removes console and physical PC hardware barriers more than most expected. Between cloud streaming, mobile gaming, PC gaming and consoles we can safely say the 1 billion collective reach for the industry is well within reach, if not surpassed. Even Playstation is transitioning to PC also, and they have their own cloud streaming. More and more game streaming services have also come online in the last few years also.
Just the way I like it. Pressure needs to be applied all over the place. I don't want Xbox running away with anything, I don't want Playstation running away with anything. I just want blows being traded, haymaker from Sony, haymaker from Microsoft. When either side is genuinely concerned about the other that's great for my gaming habit lol.