1) Deprecated for COS means we simply do not want to encourage people to use these APIs anymore. There is no requirement to merge other then hopefully the benefits in the new code that led to the deprecation in the first place.
2) Atelier has the ability to display any deprecated syntax visually and also link to its documentation, which should have some indication of why it was deprecated and what replaced it.
3) Atelier will also have full refactoring capabilities for updating deprecated syntaxes though that will not cover data migration issues as outlined in this particular case.
4) We also intend to have full support for code analysis in Atelier which can be run and show me anywhere I am using deprecated syntax and suggest solutions.