With the reveal of Gunbreaker and the small bits of information we've been given about the class, it sounds like it's magicked ammunition system will work similarly to Dark Knight's Dark Arts, but probably with multiple charges and on a cooldown, rather than just spamming.
If that's the case, then I imagine they'll be changing Dark Knight extensively so that it perhaps doesn't even use Dark Arts anymore, since it would feel quite samey. Perhaps they'll be putting a greater focus on Darkside instead?