SCH/SMN is fine the way they are, ARN was designed as a hybrid class no changes need. They even said they they may change it so that ARN will be able to queue up as a Healer instead of DPS for the pre-job Dungeons.

About the classes 2nd Jobs. The Devs have already stated a few things.

1. That equipping a Job will either swap out are alter skills as needed so they fit for the Jobs new Role
2. That they would be released as soon as all the bugs that #1 introduces are worked out.
3. That Gladiators 2nd job would be Dark Knight.(maybe) It was stated as such in the example they gave of how #1 would work.