I like the idea of Monica Bellucci (or Morena Baccarin) in the Dune universe, but doubt they'd get her for TV series (though you never know
). The late Phillip Seymour Hoffman would also have made an interesting movie Baron, or Toby Jones for TV series.
It's interesting that ever since the Lynch Dune (which I still regard as the template, though there were many good things in the two mini-series, esp CoD), they've gone with Brit Jessicas (yes, Krige is SA but made a good career as Brit). Like GoT, there's probably an endless supply of hot young European actors to fill many of the roles
. Casting director's dream.
Emily's Blunt or Mortimer as Jessica.
Joseph Rawle (Ripper St) as Feyd
Rupert Friend as Duncan
Toby Stephens as Duke Leto
Kim Bodnia (Danish actor from The Bridge) - love to see him as Gurney.
Also, the other thing a HBO/GoT-style Dune series could do, especially with the Honored Matres and Duncan in later books, is not back-pedal on sexuality.