User blog comment:MisterWoodhouse/The first specifics on the Unified Community Platform/@comment-198.189.65.254-20191016151857/@comment-24006128-20191016153000

While the projects are certainly different and will remain so after the initial migration, they will be on the same platform, meaning one authentication system. An opt-in alternative, like you suggest, would mean locking out anyone who declines to do so, which we do not see as viable.