It's true that people are drawn towards the elite, and because the largest people (tallest, heaviest, brawniest) will still be male, the most elite category will remain largely the same for people who are interested in that. I've said that people who qualify at a less challenging level are free to opt up, so that Muggsy Bogues or someone like him, maybe someone female, can move up into the elite levels--we wouldn't want to hold people back Gattaca-style. The second and third most elite categories will also have a lot of viewers, and those categories may look very different from the way they do today.
Regarding excessive number of categories, boxing and wrestling already have six categories (three for each sex/gender). I don't know that we'd need more than six nonbinary categories. Maybe four would be enough for some sports.
People don't watch the Paralympics because of a "relatability" effect that is actually "othering." Unless you are close to someone who is disabled, you probably don't "relate" to them because you see them as an other. That's just prejudice/bias.
The narrative is written by the people currently in power, and for millennia that has been mostly males. You understand the world as being divided into men and women because that is the status quo and that is what you were raised to believe. At any moment in time, there are always idealists who are fighting to rewrite the narrative, and eventually the narrative will be different. When the world is no longer gendered, girls will no longer see themselves as competing against other females. They will see themselves as competing against other people.
The vast majority of people will not be elite, and most of us accept that. We want to participate in sports just for the fun of it. We play basketball and softball at the local playground, and show up for local races, even though we're relatively mediocre at it. There's value in that, too.