As Chinthan said, in standard Personas 2.0 it is not possible to do what you are looking for. However if automation is your goal, perhaps this can help:
If you want to automatically allow all users to access Personas, I can imagine creating a group based on a PFCG role that all users have, then automate this program to run daily. This would pick up the list of all users and assign the role RENDER_ONLY to them, for instance. The scheduled run will then take care of inserting all new users into the group and assigning Personas access at the same time. It won't do Personas role deletions though...
