In reply to Justin Tadlock.

I won't go as far as saying that there'll never be breaking changes in the history of the plugin because I'm not prescient. If I deprecate something in 2016, it probably won't be supported at all in 2026. I'm not sure what that cut-off point will be for removing deprecated functionality. We'll cross that bridge when we come to it.

For the immediate future, the plan is to be backwards compatible.

The long-term plan is to hope and pray that core WP gets some sort of dependency management built in.