One part of the article reporting this really jumps out:
The actor, 47, met with Lennon’s widow Yoko Ono to discuss playing the role and she was impressed by his plans to learn to sing and master the Liverpool accent, consequently giving the project her “blessing”.
So an American actor who still has to "learn to sing" will be playing a Liverpudlian who possessed an iconic voice? I know it's called acting for a reason, but this seems like a bridge too far.
Or maybe the project won't even come to fruition. We'll watch for more updates.