I think that among the pure race bikes designed for (and marketed to) people who have illusions that their local bike club is a pro peleton and think of 25s as wide tires, rim brakes will persist.

What is changing (and will continue to change) is that these bikes will be relegated to the niche they deserve, and no longer be considered the "default" style of road bikes.

Meanwhile, among the more versitile style of bikes gaining in popularity, disc brakes are going to be the norm.