WMG / Fate/Extella Link

Per wiki policy, Spoilers Off applies here and all spoilers are unmarked. You Have Been Warned.

Astolfo will appear as a playable character in the game.

If Charlemagne is to appear as the focus of Extella Link, Astolfo, who has appeared in Fate/Apocrypha and Grand Order, is likely to appear in the game as well, either as a main character, or an unlockable one.

• Confirmed.

Nero will not be the main character, this time.

Instead, Charlemagne will be the main character and Astolfo will be his Number Two. And all of those who accused Nero of being a Spotlight-Stealing Squad will rejoice (unless they dislike Astolfo).

• Confirmed, although Nero and Tamamo still become main supporting characters.

Guessing about possible returning characters.

It has been recently stated that there are six characters that are still to be announced for the playable roster (two Archers, one Caster, two Berserkers, and one Ruler). Assuming that any of these are previously-established servants, let's make some guesses as to who these might be.

• Archer
  • Robin Hood
    • Confirmed.
  • Arash
  • Chiron
  • Atalanta
  • Alcides
  • Nobunaga Oda
  • Artemis & Orion
  • Nikola Tesla
  • Arjuna
    • Confirmed.
  • Billy the Kid
  • Sir Tristan
  • James Moriarty
  • Tomoe Gozen
  • David
  • Tawara Touta

• Caster
  • Nursery Rhyme
  • Hans Christian Andersen
  • Medea
  • Gilles de Rais
    • Confirmed. The rest are jossed.
  • Paracelsus von Hohenheim
  • Avicebron
  • William Shakespeare
  • Semiramis (as a full Caster)
  • Alexandre Dumas
  • Wolfgang Amadeus Mozart
  • Helena Blavatsky
  • Thomas Alva Edison
  • Geronimo
  • Xuanzang Sanzang
  • Nitocris
  • Leonardo da Vinci
  • Merlin
  • Circe
  • Queen of Sheba
  • Marie Antoinette
  • Charles Babbage
  • Mephistopheles

• Berserker
  • Li Shuwen
  • Arcueid Brunestud
  • Heracles
  • The Black Knight
    • Confirmed.
  • Dr. Jekyll and Mr. Hyde
  • Vlad III
  • Frankenstein
  • Jack the Ripper
  • Sakata Kintoki
  • Asterios
  • Darius III
    • Confirmed.
  • Kiyohime
  • Beowulf
  • Florence Nightingale
  • Ibaraki-douji
  • Penthesilea
  • Paul Bunyan
  • Caligula
  • Eric Bloodaxe
  • Hijikata Toshizo
  • Tamamo Cat

• Ruler
  • Amakusa Shirou Tokisada
  • Sherlock Holmes
  • Saint Martha
  • The ruler is confirmed to be new character Karl der Große. The rest are jossed.

The Ruler will be a new character.

Of the above, Shirou is somewhat possible, though it might lead to a retread of interactions between him and Jeanne, Martha is unlikely due to being a swimsuit alternate, and while SE.RA.PH could probably cheat like Chaldea, technically Rulers are supposed to be Saints.

• Same poster countering their own points, Shirou would have several other characters to interact with (Emiya would be entertaining for a few seconds), and without a Greater Grail, his plan is infeasible anyways, Martha can be wearing regular clothes and still be using fisticuffs, and since SE.RA.PH has even less to do with the Grail than Chaldea's summoning, it being able to ignore the "Rulers are Saints" just as easily allowing Sherlock, as noted above.
• Confirmed. The new Ruler is Karl der Große, and he seems to be an alternate version of Charlemagne, since Karl der Große is the German name for Charlemagne.