After I import GCM to Firebase, what happens to my old Google Console GCM project? Does it go away?
We want to come up with a contingency plan if something goes wrong with Firebase and we need to rollback to GCM for sending out notification messages.
When you import a project into Firebase, all that really does is add Firebase services to that project, and you see it listed along with other Firebase-enabled projects in the Firebase console. Nothing should change in that project that already exists at the time of import, so you should be able to safely continue whatever you were doing there.