We already know Catherine's coming to the US. Atlus announced as much. But for a game as big as this one, localization will be a key factor in its potential success. Even a Japanophile like myself knows that having a great English dub will be essential.
That's why I'm happy that Catherine's Catherine will be voiced by veteran voice actress Laura Bailey. You may know her from recent performances as Final Fantasy XIII's Serah or Sakura Wars: So Long My Love's Gemini Sunrise, or as Lust from the Fullmetal Alchemist anime, or even as Persona 4's Rise.
Personally I think she's the perfect fit for the young-and-bubbly role of Catherine, especially alongside Troy Baker as Vincent. Incidentally, Troy Baker also played Persona 4's Kanji. Perfect match, or what?
Now the big question is who Atlus will pick to voice Katherine-with-a-K. She needs to be the polar opposite of Catherine, someone who can really cow Vincent into commitment. Personally I think Jennifer Hale (Commander Shepard, Metal Gear Solid's Naomi) could do a good job.