Mark Cuban (aka BlogMaverick) gets realistic about podcasting.
I'm going to agree on one thing. Almost by definition, most podcasts are going to be in the long tail of podcasts, so will have almost no traffic. If I put podcasts in with the broader set of media options, then very few may make it out of the long tail. And, remember, long tail = no $$ for the individuals inhabiting it. (there may be a business for long tail aggregators, but not the individuals)
On the other hand, I think there are new things about podcasting, and it will open up some new forms of communications, some of which may really catch on. I think the connection with iTunes (and hence, to the iPod) goes beyond streaming because it works in a disconnected mode, which is important in our current "partially connected" world.