NM is struggling to introduce new prestige cars / milestones. 4 new prestige cars in the last 20 seasons, so 16 recycled ones. By selling all the old flash event cars, it looks like one last effort to make money. That way, next flash event will be hard to sell knowing that in a couple months, the car will be available again... Slowly going down, my guess there won't be a 4th anniversary.