Bennett always seemed pretty tiny/short on Arrow. Not that it'd matter that much, movie magic and all, just do what they do with RDJ, but still.
You do basically have to cast a New Zealander though, given all the backstory in place now. Morrison would be great, but you probably wouldn't want him ever taking off the helmet if it's set pre-OT, the age doesn't really work.
Pretty psyched for Mangold though. I always really wanted Joe Johnston for this (given how much the design owes to him), especially given he was their other go-to guy option other than Howard to come in to fix Solo. Man it sucks how his career's pretty much petered out after The First Avenger, that Narnia movie nobody's going to see being his final directorial effort is pretty depressing.
But no way anyone's going to complain about Mangold, this is right up his alley. Make it small-scale like Solo (maybe a little bigger, middle of a gang war, but keep any big galactic ramifications away from this), with more of a western feel.
Come to think of it, both a Boba movie and an Obi-Wan movie should be westerns. Just in different ways.