I feel that they are going to AAD to the game as like a 2nd Arc Drive on every character maybe except like Saber who already has one.
Mainly because like, I still think its weird they don't make a reference to Arcueid Moonsault Dive from her battle with Vlov. When its the key promotion art for Tsukihime Remake and her NP Animation in FGO.
For others they can probably bring back old Last Arc or Arc Drives from the old games too. Like Ciel's Exploding Keys, Miyako Big Punch, Hisui's Brainwashing Detective thing, Or new stuff for them that was added in the Remake. Like Shiki's Death Ground Stab or P.Ciel Virgin Pain Armor Super. If they are gonna bring back the collab character like Mash, can probably give her Lord Chaldes/Camelot as like a Super Armor Buff Super.