He's still in the honeymoon period. Everyone is optimistic at this stage. My guess is that within a year or two he will leave, disgusted by the subtle erosion of the Zappos vision.
Some more of the Zappos vision might actually bleed over into Amazon (the article mentioned the Amazon distribution center that followed the "$2000 to quit" Zappos approach).
Well, he is still growing, which is good, and likely to lead to a hands-off approach by Amazon. Amazon might just let them work things out, rather than integrating them too much into Amazon.