We talked a lot about whether or not we should go back to a zero mana cost W on Kog. We decided not to in 6.19 at least both to get a better understanding of where Kog's power level would end up post partial revert and because of some concerns about the impact of a no cost W. It was a change we were never entirely happy with, given it both changes the meaning of what mana/being OOM mean on a kit and added quite a bit of laning power to a champion intended to have a lot of late game strength. It's certainly possible we add go back to it if Kog needs buffs after these changes, might be other buffs though that are better options.
In terms of possible changes in 6.20 we're waiting to see how Kog performs over the next few days at least before we talk about whether we should try and do anything power wise in the next patch or not. We will definitely be changing his W animation back to the pre-update one, that's basically just a feel change though, so doesn't need to take his balance state into account.