The actual release date, and the push through various beta phases will highly depend on player feedback.

If the game is unbalanced and rough in phase 3, and the players testing it speak up, then it will be fixed before it is pushed to phase 4, regardless of how long this takes.

The point of testing is to ensure everything works before it is put in stores. If the game is unbalanced, it won't be pushed forward. Hence the lack of a release date, as that date is still unknown.