The BloodRayne: Betrayal material is the most phoned-in I think I've ever heard Virt sound. But then he went and did Mighty Switch Force, his best work, so that sort of balances it out. I guess it'd have a chance to be interesting if he sought to avoid the stylistic typecasting of endless pipe organ arpeggios in a symphonic rock mold in any hypothetical Castlevania project of his, but only then.
Sakimoto is a good choice. The man is nothing but class. Some other prime candidates: Masashi Hamauzu, Yousuke Yasui, Shinji Hosoe, Masafumi Takada, Kow Otani, Kenji Ito, Takayuki Aihara, etc. I realize some of these folks aren't representative of what necessary strikes as immediately "Castlevania", but I'd rather there was branching out for new, experimental things instead of letting the status quo trod along. I'm sick to my stomach of Judgments and Harmony of Despairs.
Past composers who are still active in the industry that I'd like to have for another round: Sota Fujimori, Yasuhiro Ichihashi. Soshiro Hokkai, you were too good for this world.