Under the assumption of 25 characters based on the cards. Asterisked characters are predictions.
Rowan
Lianna
Chrom
Robin
Lucina
Fredrick
Lissa
Cordelia
Tharja*
Corrin
Azura*
Ryoma
Xander
Camilia
Hinoka
Takumi
Leo
Sakura
Elise
Marth
Caeda*
Tiki*
Jaegen*
Draug*
Anna*
If it's 28
26. Another Shadow Dragon Character (Minerva or Merric)*
27. Another Fates Character (Kaze, Niles, Felicia, or Oboro)*
28. Another 13/14 character (One of those/ Gaius, Virion, Panne or Olivia)*
Assuming that Villians will be in an update and DLC will bring Echoes, 7, POR/RD, and more 13/14 characters.