I don't think there will be any new styles? The D-pad is going to select the styles for Dante - Trickster, Swordmaster, Gunslinger and Royal Guard. So there isn't room for anymore styls. I suppose maybe you could get other styles, and then set them up beforehand, so you could assign UP on the pad to be quicksilver and LEFT to be doppelganger... but we haven't heard about that, so I kind of assumed there would only be the main 4. And as Nero has been so well-thought-out, he has no styles... great! -_-
Having said that, I would like to see more for both Dante and Nero that would be cool. For Dante:
Quicksilver - have a few more things he can do with it, like freeze individual enemies for a long time for like 1 or 2 orbs. Or freeze a radius of enemies for more orbs.
Doppelganger - Again, I'd like to see more options. Maybe have it so that circle makes the doppelganger attack - so you don't activate him and have him for a set period, you can attack whenever and it uses orbs as and when you press O. He would attack with the weapon you have equipped (or maybe to make things interesting he would have the opposite equipped?? Hard to keep track of, but would make more variety). So you can press triangle and O together. But with each attack you do with O, it drains orbs off you. Maybe each attack could take off 1/4 of an orb. That would make for some extreme combos! So maybe in doppelganger style, you have 2x Dante all the time, but he just follows you around until you press O, then he performs an action. Either that or he could pop out just when you press O, then fade away, either way is cool.
Grappler - This would be cool and would allow Dante to grab hold of enemies at close range and do wrestling moves on them. He could have a few different things he could do depending on which enemy it is. For the really massive enemies, he could just grab them and do knees / headbutts etc. But for small enemies, he could do DDTs, Powerbombs, Suplex, and even do stuff out of the air.
Infuriator - This would be like an ultra taunt style. As well as your normal taunts, you would also have O for more taunt moves. They would be cheesy stuff like slapping them around the face, or kicking them in the balls, poke to the eye, moonwalk, handstands etc - do low damage (or none at all), but they give you orbs back quickly. This would be really funny, but also useful because obviously you'd be able to use DT more often.