I mostly agree, but I've seen a few, new modern lever actions shown.
The new S&W lever action, if you spend the money for the wood version, is vaguely cowboy.
Also, the Winchester Ranger is a new 22cal lever action and it is very cowboy.
edit: Taurus apparently introduced a SAA clone as well.
edit2: Cimmaron finally released it's new 1887 Shotgun