According to 1UP.com’s Jeremy Parish in reply to Red Draco’s LiveJournal, it would seem that the US version of Rockman ZX for the Nintendo DS will lack a localized voiceover, instead rendering the included anime cutscenes with subtitles over the original Japanese dialogue, perhaps not entirely unlike Mega Man X6 (not including the Mega Man X Collection version, which did away with those voices as well), and cutting down on any voicebits in gameplay to mere grunts, similar to the localization of Mega Man X5.
MegaMan ZX is set to release in the US on September 12th. Via Retrofaction