So as more English voice actors are revealed for Three Houses, some folks have noticed something that may mean something.
A large amount of the voice actors picked for characters in Three Houses also voiced characters from Genealogy of the Holy War in Heroes. Allegra Clark was Ethlyn, Robbie Daymond was Ares, Faye Mata was Lene, Laura Post was Silvia, Erica Mendez was Deirdre, Cassandra Lee Morris was Julia, Christian La Monte was Seliph, Joe Ziega was Jamke, Griffin Burns was Julius, Ratana was Ishtar, Chris Hackney was Quan, and Abby Trott was Nanna.
In addition to those, Ben Lepley played Saias, who appears in Thracia but not Genealogy, and Cristina Vee (who was the original voice of Edelgard before she was replaced by Tara Platt) played Lachesis.
Granted there are a few important VAs who haven't been confirmed for Three Houses yet, namely Grant George, Brina Palencia, Mick Wingert, Xander Mobus, Nicolas Roye, Robert Clottworthy, and Steve Staley, but that's still a huge amount of FE4 character VAs.
Add in the fact that Genealogy is the oldest game that hasn't been remade, and...well, I think you see where I'm going with this.