Yeah, I wouldn't hold out hope that gomu-gomu would ever be used in a dub. Especially by Viz, since they translated it as Gum Gum in the first place.
I really don't think such literal translations would do well at all, and they'd serve only to appease die-hard OP fans. If we want the dub to be succesful there'd be alot of things that couldn't be literally translated.
And say the dub was made as close to the original Japanese scripts as possible. In addition to alot of issues with timing, syntax, Japanese word-play etc., we'd have another issue and that is: If the DVDs offered both Japanese tracks and an almost-exactly the same dub, what incentive would companies have in making the dub at all?
So the big question with the handling of the series is whether or not One Piece would be on tv (where it'd not only need a dub, but a dub that caters t omore than just die-hard fans) or on DVDs only (where they can be a little more free with the dub, and could even not include a dub at all if they chose to)
OH! and before I forget.
Wondercon, big comic book convention in San Francisco, on March 2-4. VIZ will be having a panel on the 3rd, where they'll be talking about upcoming titles and other announcements they have.
While it's a long shot they'd even mention One Piece aside form the manga, if I can I'll try to speak with some of the VIZ people and see if I can get any info out of them.