It really would be nice to have Scott Menville. From what I understand, the original VAs couldn't be used for Radiant Mythology because Symphonia's dub was a Nintendo-exclusive, so I sort of don't see why they can't bring Menville back since it's on a Nintendo console. But I don't know much about the logistics of getting these actors together so I won't make a big fuss if they can't bring him back, which looks like what will be the case.
That doesn't make much sense, because AFAIK Raine has the same VA in RM, at least. Her and Tear also have the same VA anyway.
That said, I think it's either one of three things.
1) Menville could be too expensive for Namco's budget (or, cheapness).
2) Menville may be a union actor, and for some reason, some companies have been steering away from union actors in the last few years. Etna got a new VA in Disgaea 2 for this very reason, apparently. :/
3) Menville may no longer be in the area. This is a problem because companies tend to prefer working with local studios. At least, that is my impression.