Speculation: who, if any, will be new Servant in Chaldea. Clearly, it's not free David we got for some reason.
1. Drake: one of the strongest Riders in the game, and has plenty of narrative investment. Also pretty ironic to have on tap in London, and to some extent, in USA. Chaldea also does not have Rider at all. However, she is pretty tied to naval theme, and i doubt her NP can be played strait as ghost guns appearing behind her. So i would not expect her.
2. Asterius. Chaldea also has no Berserker, and he also has decent narrative investment. However, character-wise he pretty tied to Euriale, and she clearly has no interest in Chaldea, and also no need of 3rd Archer.
3. Medea. Absolute mood kindred to Taylor, and my personal favorite here. Also voiced investment with working with Taylor. But she pretty much copies El Melloy narrative niche as low-combat, high-utility "scientist" (exposition girl) so, sadly, i doubt we get her.
4. Honorable mention: Heracles. Greatest hero as perceived by west. While awesome to get, he either absurdly OP, or non-character beatstick, therefore has no chance to be here.
5. Honorable mention: Caenis. We have precedent of summoning Heroic Spirit who was an antagonist previously. She shown enough interest in Aife to come to Chaldea. But given potential of Team A, i doubt we see her any time soon.
6. Hektor. Very interesting character, with enough spotlight on him. Lancer that is not win-button as Aife, so he can be used more freely. IMHO most likely to be taken.
7. Orion (Artemis). For some reason, Taylor content to watch her from afar, and does not talk to her at all. Twins seemingly ignore her entirely. Narrative seems to want nothing with her, no matter how much stuff going on (goddess, knows enough about Servant system to hack it, strange bio-mechanical elements). Negative chances for her.