I don't see the Classic going away anytime soon. People who buy it just want raw storage -- they don't care about cameras, multi-touch, wifi, etc. Being as it is the "iPod Classic" it doesn't require any significant changes. Just drop in a bigger 1.8" HD on a yearly basis and it will keep those customers happy. There are still lots of people who want to carry around their whole library.
I always thought iPod a bit of hype. Either it should be iPod shuffle of the iPhone, others, even iPod touch are unlikely to survive