Although I do agree that the CBIR is a fantastic course, I don't believe that it will make the old IMC obsolete. In order to get a CBIR you need
1. 7 Ground Exams
2. Class 1 medical
3. Validate it every year
AIUI you don't need a class 1 medical for the CBIR, just the class 1 audiogram (which can be appended to a class 2 medical)...