I don't think 29er is dead and the race scene will make it survive since the point is to finish first despite the bike feel good. Most likely the industry will try and eliminate normal size tires (anything under 2.4) and a few years from now come back around to normal size tires. I can see 27.5+ surviving all of this and fat bikes going out of style when people realize that they are stupid for just normal trail riding. @jimvreeland is the exception here because he is at a different level.
I'm going to disagree here. I got to watch @woody kill it all summer on his brothers 30lb plus Fatboy. He had no trouble keeping up on the hammer rides and rode everything and more on the tight & techy stuff. They're no longer a winter only bike and do make good trail bikes.
I think the point Jim was making about the death of the 29er is that the XC crowd is a really small group. Most people just go out to ride their bike for fun and these fatties make riding easier which is more fun to most. I think the 27.5+ is going to take off & possibly be the norm for trail bikes in a few years.