You said the current 5.x-dev breaks with contributed 
modules. But you don't see a reason not to release it?!
It's been quite common that contributed modules have required some updating along with the Drupal core upgrades (even the incremental ones). If there is a new policy which says that a Drupal core upgrade should never result in any contributed modules being broken, that seems like a new precedent. Many people will welcome the backwards compatibility, but I it seems like a lofty goal given the many changes to the codebase and/or database.