Well they said in the Q&A with Rory that they would give Vaal arc a buff to arc on top of its usual stuff and that because they moved the former "will target an additional target each chain" aspect directly on the base skill, it'd be new. Not entirely sure what the wording means, I'm thinking it only means lucky crits on arc, which is still great because of all the other shit. Vaal arc is going to shock the fuck out of bosses too probably with all these modifiers, so you'll get a huge damage boost from that shock.
It's nice that they weren't too scared of overbuffing stuff with this patch. They could have went with a series of garbage buffs like that one time they said they would buff a ton of skills and then they gave Glacial Hammer 7% more damage and shit. They're for sure going to miss the mark on one or several of these skills and some of these old ass skills are going to be top tier meta again and then everyone will whine to nerf them, but at least it'll shake up shit for a while, and it's cool to go back to using beta era skills and not have them be some hipster shit build just because.