For 2017.5, we are planning on changing all of the action names (self.name) to use hyphens to separate words instead of the current mix of hyphens and underscores. This is to make future support more consistent.
All V2 templates currently in upstream will pick up these changes as part of the review process.
Any V2 templates which are not upstream and which reference timeouts for specific actions may need adaptation, however, note that 2017.5 also moves a lot of the timeout settings to base.jinja2 anyway.
If you have test jobs which reference specific actions, these will need changes too.
We're implementing a change in the dispatcher codebase which verifies that underscore is not used in the self.name of any class inheriting from Action, so all code reviews will also need updating.
https://review.linaro.org/#/c/19027/