Oozie primarily depends on the job end notification to determine when the job finishes. In the current version, job end notification is implemented in job tracker. Since job tracker will be removed in the upcoming hadoop release (.next), we wander where this support will move. I think this best effort notification could be implemented in the new Application Manager as one of the last step of job completion.
Whatever implementation will it be, Oozie badly needs this feature to be continued in next releases as well.