I've only seen three episodes (in microscope format
on GBN, though) of EGB (at least, I don't think it ever got to the screen in The Netherlands), and I must say, I really like the artwork and I really like the concept. If a GBIII were to be made (with indeed an older looking original cast) Dan & Harold should use the EGB concept, preferably with the same characters as in EGB, since I thought they were definitely better than those weirdos in that script of Dan's everybody had been talking about. I dunno make a blended version of the first EGB episode and that episode where the RGB come in. It should make a good story, turned into a film it could be really good I think. And a mix of two stories needn't be that bad. If you take the Asterix comic films, most of them (apart from the first two and the 12-works one) are made up of two original storylines from the comic books mixed together and turned into one. These films are great as well!
Anyway, if this thread had a poll: I'd say YES to GBIII based on EGB.