The whole deal of a HD that rides like a caddy may be a lot harder than one things. Think about the rancher that stacks hay bails on at 3500 dually 3 or 4' above cab level or a 11' camper. A narrow stance suspension spings or air bags are going to have a hard time. Time will tell if I am right. But I still go back to what they said in 2003 about moving spring out and no need for sway bar.
Regarding 2500 and its narrow stance of suspension, that makes for a better ride, allowing a wheel on one side to handle a bump better. Just do not put a tall load on it, as the guy with the 9' foot camper did and had major handling issues.
Therefore the 3500 air is on hold, as they have to be able to handle all uses! 3500 are not grocery getters! Snoking