Arc becomes Bard, loses its damage potential in parties, obtain increased buffing potential in parties, retains its dps superiority while used as a class.

Melees become heavy dps jobs, obtain increased damage potential in parties, become the king of dps while used as a job, retains tanking superiority over arc while used as a class.

I don't see a problem with ARC. I can see an issue arising with BLM however. It'll be a CC job, but nuking leaves something to be desired still. They need to figure out something else for that issue.