I've discussed this concept with my son, who has a degree in urban planning and actually works as an urban planner. Among the things he learned in school, is how to guide (herd) people in directions they may not want to go. How to design cities to eliminate personal vehicles etc. Academia is already aligned with the powers that want to control the masses.
I envision the 15 minute city as the 21st century version of a medieval village, extrapolating for the exponential growth in population. My impression is the medieval villagers probably worked and did all their business within 15 minutes of home, as most probably did not have any transportation due to low incomes. The same situation applies in the 21st century, many city dwellers don't have sufficient income for a personal vehicle.
The 15 minute concept was applied to the Ellicott Complex, part of SUNY at Buffalo. It is a residential complex that allows students to attend classes, eat, shop, bank, and be entertained without going outside. In my opinion, it is like a maze, and we joked that it was designed to lessen the chance of riots as the University had been the scene of some violent anti-war protests in the early 70's. Here are some photos to give you an idea of what it's like:
https://www.davisbrodybond.com/suny-buffalo The big question is how those that reside in rural areas are going to fit into the 15 minute city concept. The answer, of course, is that we won't. Going Galt is looking to be the best alternative. Who is John Galt?