I think the update will see many plays with GK's. As far as I saw, this update opens up new lockdown plays to slow down the game, and once you slow it down your opponent has to get through the multiple obstacles to take the leading again. I mean just look at the new cards, along with Necrovalley presence it is hard to deal with GKs. Many new ways to thin the deck, wreckage cards like Royal Tribute out of no where, Shaman being able to be summoned through Spy and Disciple to protect Valley, Ambusher being able to abuse opp graveyard + Descedant will now abuse him to destroy a card then ambusher will get you necrovalley again etc etc. Simply awesome lol.Combine that with some awesome XYZ options and tech cards such as Malefic Cyber End lol, this archetype can be played in multiple ways but I believe people will find a suitable way to play them competitively. I mean it is a deck that has many options to lockdown your opponent having that antimeta style with Shrine and Necrovalley while Descendant and others make sure they can erase problems in the field while also being able to deal high damage because of increase in ATK by necrovalley, GKs now have good support to move on at least to the extent that you can play them again.
I am not playing anymore but if I see more potential in these I might return to test this deck out since this is my no1 archetype since I started playing back then in 2003 lol.