I don't think BoRK is an issue at the moment at all. The only champion I see majorly abusing it is Lucian which is no surprise. :/ He's consistently abusing items that get buffed which makes me wish that they would look at Lucian instead of nerfing an item for an entire class of champions. Lucian, in my opinion, is the problem and needs to be reworked or looked at because the armor pen issues started with Lucian and the BoRK issues also did as well.
And for anyone who says BoRK was "fine" before they buffed, you're literally just saying that because it was watered down and weak as shit. BoRK was a fairly weak item all of season 6. The last time I remember BoRK being viable was season 5 and it was a core item I built on Tristana; IE, PD, BoRK is what I used to do in Season 5. Now I can reliably do that this season as well. IE, Runaan's, BoRK and she's not half as awful in the midgame as she usually is.
Just as proof that BoRK was not fine before they buffed it, do you remember when it used to be a core item on Vayne? How many Vayne's did you see build it in Season 6? Or for that matter, when Vayne was strong, how many built it then? BoRK has been bad for a long time.