The intrigue and mystery of Arabasta/Water 7 is peak One Piece storytelling and Egghead is starting to remind me of it a lot. That's exactly what we needed. The real and fake Vegapunk plotline is bonkers, hopefully it delivers. As to who could be the one shutting down the defenses, there's a plethora of characters that are able to do such a thing, with majority of them being blackbeard pirates.
Kidd landing on Elbaf and Shanks being there with Dorry and Brogy is epic hype for me. I wonder if those two have gotten stronger since the pre-timeskip. People dis Giants for being fodder, but destroying a gigantic sea king with hakoku requires a lot of power, power that Strawhats of the time didn't have. Getting back to Redhair pirates, it's logical they would be at Elbaf with the whole norse theme. I don't know in which direction will Kidd and Shanks' meeting go but I doubt they will do more than a short clash. If the giants speak well on behalf of them defeating BM, I wouldn't be surprised if Shanks doesn't attack them. Logically, they should be quite worn out after the battle in Wano, so who knows.