There are two major roles, and I'm told that for Tetsuo, Robert Pattinson, Andrew Garfield and James McAvoy have been given the new script. For the role of Kaneda, the script has been given to Garrett Hedlund, Michael Fassbender, Chris Pine, Justin Timberlake and Joaquin Phoenix.Err... disregarding the number of talentless pretty boys in there, aren't the two lead characters in Akira orphaned teen street punks? Yeah... why are we looking to cast people between the ages of 28 and 34?
Here's where we're likely to run into what I now dub the "Enders Game Principle": the reality that the source material contains elements that won't get past societal norms/beliefs and therefore must be purged to make it acceptable. As such, Tetsuo and Kaneda likely just gained 5 to 10 years to make them into the grizzled motorcycle gang members people are familiar with from TV.
Be prepared to find the film presented from that context.