Just to put in my Two Cents ;)
I personally belive that that Kurts Balls may not be part the game anymore but that he may act as a trader between to get the DPP pokeballs (Quick, Dusk, etc.) for their GSC Counter Parts (Fast, Moon, etc.) when you give him the apricorns, since they will most likely be Key Items now.
I highly doubt that Dive will become an HM again for the same reasons that we couldn't transfer pokemon over with HMs from 3rd Gen, because their commands not to make then unereasable remained.
Hopefully, like others have said, they will have Extreme Speed Dratini and increase the usefullness of Kanto, although I really do hope that the Sevii Islands do return since it would be a waste not to use the trading center on Island 1 as the GTS hub for it, although the Goldenrod Pokemon Center could also fit the description ;)
Outside of these things, It's going to be interesting how how they treat the time machines, the closed safari (maybe add a sidequest to open it?), what the shiny pikachu unlocks(if anything at all), the usefullness of the new aesthetic traits and the art like others have said.