I previously wrote about the Asterisk Module Deprecation process and policy but since that time some additional policies have come into existence based on the request and feedback from the developer community.
The new feature and improvements policy more clearly outlines the requirements for inclusion and also gives the project the ability to reject a new feature or improvement. Some changes just are not applicable to the vast majority of the Asterisk community, and can impose additional support requirements on Asterisk developers. This policy does provide a way to re-visit such a decision if it occurs.
The bug fixes policy more clearly states that a fix can be reverted if it causes a regression and also outlines a desire for test coverage if possible. The more test coverage the Asterisk project has the better.
Finally the C API deprecation policy allows C APIs to be removed from Asterisk, but is based on the module deprecation policy so this can only occur initially in standard releases. This gives developers who have modules outside of Asterisk time to update and provide feedback.
I urge you to take a look at these so you can be aware of the policies in place for the project.