Convert Parent Summary Field to Standard When There are No Subtasks

A project may have tasks, and then tasks with subtasks.

I want to be able to use Show Summary on Parent Item (Status) for tasks that have subtasks, but have that Status field convert to a non summary field when there are no subtasks.

Otherwise, I need to have duplicate fields for status, Start Date, End Date, Estimated Hours and virtually any other field I need to track.

This is vital for a true PM application.