Apparently Dwayne The Rock Johnson had this to say to AOL:
8. What can you tell us about 'Jonny Quest'?
Right now we're just still redeveloping, if you will, what that movie will be. That's with myself and Andy [Fickman] and Zac Efron, but it's still in the developmental stage. Zac is my buddy -- I like Zac -- and I think that we would make a great pairing.
I have no idea where this came from, but if it is true, I expect we might here this again elsewhere as both Dwayne and Zac are doing promo.
Jonny Quest was an animated Hanna-Barbera series where Jonny Quest was a kid who went on all sorts of adventures. It also had a spinoff The Real Adventures of Jonny Quest which featured Jonny as a teenager.
The script for this was on the blacklist last year which means it is a pretty hot property. So it could be a really good project. I think that version of the script had Jonny as a kid so the redevelopment is probably retooling to make Jonny a teen for Zac to play.
Of all the comic/manga adaptations this is not the one I'd choose for him, I'd choose Death Note or Harbinger. But he needs some variety. Plus if the movie is with The Rock, it doesn't put all of the weight of its success on Zac. So it might be a good transitional film.
I'm interested to see how Race to Witch Mountain goes to see how The Rock's box office is trending. If it does great, it speaks well for this project. As long as it doesn't get out of control, artistically speaking, like Speed Racer.